Actors, obliged to exhaustively market their wares, will pose for hours in front of posters of their latest film or TV show. They’ll hop between city premieres, sit on dreary festival panels, tell rehearsed comic stories on night-time talkshows, then get up early to be on breakfast radio. Before meeting Omar Sy, a 43-year-old Frenchman who stars in the massively popular Netflix drama Lupin, I’d never heard of an actor picking up a bucket and brush to spend a day gluing up their own billboard posters on the Paris metro. Sy, who is 6ft 2in, born in a working-class Parisian suburb to West African parents, explains the thinking behind this unusual marketing stunt that took place just before the first series of Lupin debuted earlier this year.

“A lot of people know me in Paris,” begins Sy, who worked as a comedian in France through his 20s before becoming a film star there in his early 30s. “Because people in France have watched me in stuff for years, I’m used to meeting strangers who recognise me and who already have smiles on their faces.” In Lupin, lightly adapted from the classic heist books by Maurice Leblanc, Sy plays a French-Senegalese man called Assane Diop, an anonymous Parisian who is used to being ignored and overlooked in his home town, but who is willing to use that to his advantage while robbing the city’s jet-set blind. “The show is entertainment and we want to have fun with it,” he says, “but at the same time we’re talking about something very serious: that some people in France are simply not seen.”

Stuck for marketing ideas, the Lupin team wondered what would happen if the locally famous Sy dressed up as a maintenance worker, slapping up posters. Would people know it was him, wearing the uniform of a low-income worker, before a giant poster of himself? Would they smile?

Sy stresses that the stunt was only ever meant to be playful, and some of its efficacy was probably diminished by his having to wear a Covid mask . But even so. “The smiles disappeared. People were sort of… rude? And it proved to me something we were saying in the show. That sometimes, in our society, you can be invisible because of what you do.” Worse than invisible, too. “It took me back to something I used to experience as a kid, coming up in Paris, when I experienced a certain kind of a look from people.”

What sort of look?

“You know the expression, ‘breaking the ice’? It’s ice,” he says. “Because when you come from where I come from, in the suburbs, when you have my height, my skin, that ice – it doesn’t break easily. Actually, I think it started me on the path to what I’m doing today. I remember as a teenager I wanted to see smiles on people’s faces, not the suspicious look. One way to do that was humour.”

As early as 14, then, when he was already pushing past the 6ft mark, Sy learned the complicated lesson that for better or worse he could put anxious strangers at ease by cracking jokes. “Plus, it was very effective on girls. So I tried to become an expert.” Before he’d formally graduated from high school, he was gigging on local radio, having some early success as an impersonator and sketch comic. As he got better and got more prominent bookings his studies suffered. Though he was supposed to finish school at 18, he still hadn’t passed the baccalaureate by the age of 20.

That year, a French TV channel invited him to go to Cannes, a month before he was due to sit his baccalaureate again. “I was in Cannes! I was working on TV! I saw the stars!” But he came home and failed the exam. Sy remembers a showdown with his parents. “We were in the home I grew up in. The whole family was there, after dinner.”

Sy is the middle child of eight, most of whom work around France as hospice workers, teaching assistants, receptionists, chefs. Before they retired and returned to Senegal a few years ago, Sy’s parents held exhausting low-income jobs. His dad worked in a factory. His mother was a cleaner. All 10 of the Sys were present, he remembers, on the day he sat them down after a meal and said – cough – he planned to be un humoriste. “I could see they were worried,” he says. “No, scared. They were certain it wouldn’t work out, but they are very cool and intelligent, my parents, and they knew they had to let their children live.”

Getting out of the suburbs and making it in a competitive profession never seemed completely impossible to Sy, because he’d watched a close friend do it. Nicolas Anelka was the best footballer at Sy’s school. He was the boy in their gang of mates “who was always going to bed early, before training, while we were out partying”. Aged 17, Anelka left Paris for London to play for Arsenal, where he became a global sensation. Sy watched every one of his friend’s games, “proud but not surprised” at this ridiculous example of success. Meanwhile, Sy ground out his own screen career, getting what parts he could.

He starred in a TV sitcom about call-centre operators. He voiced the fish in a cartoon called Fish & Chips, he took small parts, and he appeared in a few films, including those made by the emerging director-collaborators, Olivier Nakache and Éric Toledano.

As Sy was convinced he was a comedian at heart and that he had not much clue when it came to straight acting, Nakache and Toledano had to encourage him on their sets by saying: it’s cool, we’re only pretending to be directors ourselves. The trio became good friends over the years, and “Each time they had a movie,” Sy remembers, “they put me in it. The roles got a little bigger. One day they said to me, ‘Now you’re an actor, Omar, not just a comedian. We’re gonna write a movie for you to make you understand that.’”

During these years Sy’s own family was growing fast. He met his wife Hélène (a charity director) in the late 1990s. The couple went on to have five kids. They moved west out of Paris to a smaller town called Montfort-l’Amaury. Some time in 2010, the filmmakers Nakache and Toledano sent over that script they’d written with Sy in mind.

Adapted from a documentary called À la Vie, à la Mort, the movie told of a white, wealthy man who is severely disabled (one sort of “untouchable”) who develops a friendship with his caregiver – black, male and working class (another sort of “untouchable”). Intouchables was unapologetically sentimental, lightly political, with a joyous centrepiece dance sequence that Sy choreographed himself. It was a smash in France and abroad: the highest-grossing French-language movie ever made. “My life, everything I’m living, in a professional way, has come from that movie,” Sy says.

Only when Intouchables came out did his parents stop worrying about him, Sy says. And they’ve more or less stopped paying attention to the ins-and-outs of his career ever since. When Sy moved with his family to Los Angeles in 2012, taking roles in a $75m Tom Hanks movie (Inferno), a $150m dinosaur movie (Jurassic World), a $200m superhero movie (X-Men: Days of the Future Past), “my parents had no clue what I was doing. The [box office] numbers, all of that… It was too far from them. It’s been a blessing for me. If I’ve been able to stay the same guy I was, feet on the ground, it’s because my parents still have no clue what I’m doing. For them, all that matters is: can you live from it? Then it’s success. There is no other stage. Can you make your living from it? Then it’s success.”

After a decade working mostly in Hollywood, Sy’s Lupin – one of Netflix’s most-watched shows of 2021 – has marked a homecoming of sorts, geographically and politically. Filmed largely in Paris and the northwest of France, Lupin grapples cleverly with the racial dynamics at play in the French capital, just as Intouchables once did. Sy’s character Diop, a charming thief, seems masterfully confident. But we learn through flashbacks that his life is defined by his experiences growing up as an immigrant, encouraged to keep his head down and defer to white Parisians. As for Diop’s relationship with the French police… Well, at least once, he is able to rely on their inability to distinguish between Black men in order to evade capture.

When Sy was a teenager in the suburbs, he explains to me, he had a complex relationship with the French police himself. As a rule, if he crossed their path, he judged it best to run, because however guilty it made you look it was better than letting them get their hands on you. “I remember dealing with that as a young man. And 20 years after? It’s the same [for other young men]. Nothing’s changed.”

Back in 2016, in circumstances horribly similar to those of George Floyd in 2020, a French-Senegalese man named Adama Traoré died in police custody. His family believed the death to have been caused by asphyxiation, and Sy has been involved in their campaign for answers and accountability ever since. Last year, when Floyd’s murder prompted waves of protest around the world, Sy wrote a searing open letter in the French press, comparing the cases. “They were both Black, tall, their lives turned to horror in a few hours, for nothing,” Sy wrote. “I am tall. I am Black. I look like them. Can the same thing happen to me as to them tomorrow? Is this likely to happen to my children?”

“Most people who read the letter understood it,” Sy says now. “Some people didn’t. There are people who’ve said they won’t watch my movies any more in France. I knew when I wrote the letter that it would affect my work. But I had to do it. I had to do it. In my position in France I had to say something to young men who look like me.”

I ask him how he talks to his children about this stuff, especially his teenage sons Alhadji and Tidiane. “I say, ‘You have to face it, try to find a way to fight it, and as early as possible. Because more is coming [as you get older]. More is coming. So you need to find a way.’”

We’re talking about his life as a father, and what it’s been like for Sy’s kids to go from a childhood in France to teenage-hood in America, when he corrects me on a point of fact. I had assumed, because of the timing of the family’s emigration, that this was a climb-the-ladder move. I guessed Sy made the switch to America in search for bigger parts, for fame. Actually it wasn’t quite like that, he says.

Before it became a worldwide hit, Intouchables was much talked about in France, and Sy’s level of recognition shot up overnight. (He won a César for best actor, beating The Artist’s Jean Dujardin that year.) Suddenly, the comfortable life Sy and his wife had built changed. He noticed it in the school playground, picking up his son, Tidiane. “Before, I was always just thought of as Tidiane’s dad. And one day I went to pick him up and I realised, ‘Oh, now Tidiane is thought of as Omar Sy’s son.’ I got scared by that. I told my wife, ‘I don’t know how to raise a kid in this way, with someone else’s fame hanging over their head.’”

With Intouchables longlisted for a foreign-language Oscar, the stars of the movie were asked to begin a campaign in LA to generate support. Sy might have gone there alone, but he took his family, intending to stay a few months. Quickly he realised how much happier he was there, anonymous again, just an appendage to his children at the school gate. When I ask why, Sy speaks again of his own parents: Dad, the factory worker; Mum, the cleaner.

“I think it builds your relationship with your parents when you have to explain to people who they are and what they do for a living. It makes you think about who they are beneath the jobs. It connects you to them. I remember having to explain what my mum did when I was Tidiane’s age. When I told people she was a cleaner… Well, I went through different stages with that. For a long time I was ashamed. Then, growing up, explaining it over and over, something changed. Talking about my mum and her life made me feel more connected to her. Expressing stuff helped me to realise things. And I was so proud of her.”

Sy shrugs. In America, in playgrounds, he gets to be the parent in the background. And his kids get to work out the rest for themselves.

Lupin Part 2 is on Netflix from 11 June