NEW YORK — “That was Robert De Niro’s booth; Al Pacino would sit here, Johnny Depp and Kate Moss sat there.”

Michael Cecchi-Azzolina, a short, excitable man sporting an early-Cher wig, gestured toward the booths and banquettes inside the packed bar area of Raoul’s, a French bistro and discreet celebrity hangout in SoHo that recently celebrated its 40th anniversary with an unusual dinner party that brought together regulars and former servers like himself.

“I was a waiter here for 20 years,” said Cecchi-Azzolina, who now runs the West Village restaurant Bobo. When asked why he stayed so long at one place, he spread his arms out and tried to embrace the room. “This is all my family.”

It’s not often that you see waiters and busboys hugging patrons in a New York restaurant, but that was the rule at this epic, 10-hour birthday bash that doubled as a family reunion for a SoHo institution that remains a refuge for the neighborhood’s bohemian old guard.

Opened in 1975 by Serge Raoul, who was a sound man for France 2, and his brother Guy, who was a chef, Raoul’s is the rare family operation that caters to actual families, as well as waves of actors, producers, models, journalists, gallery owners, designers and other assorted downtown glitterati who have made this their living room for four decades.

Raoul, 78, is now retired and living in Nyack, New York. His son, Karim Raoul, 37, started managing in 2010 after his father had a stroke, and is keeping the family’s social legacy alive.

“We wanted the real regulars in tonight: those people who had 90 reservations and upwards,” said Karim Raoul, as he made his way through the packed bar, shaking hands and squeezing shoulders of old friends. “We have three generations of customers: the parents, the grandparents and the kids.”

Raoul’s started off as a place for his father’s journalist friends to hang out after restaurants in the neighborhood, then quiet, shut down for the night. SoHo artists and dealers from the budding 1970s gallery scene adopted it as their boozy canteen. It got its first taste of celebrity a few months after opening, when a young TV producer named Lorne Michaels arrived with his troupe from “Saturday Night Live.”

“I worked at ‘SNL’ from the inception with Lorne and John and Danny,” said James Signorelli, 73, a producer on the show for decades, referring to John Belushi and Dan Aykroyd. “At that time we were finishing up our work at 11 p.m., and no one was serving. Then we discovered Raoul’s, and it was like going to heaven, and we were here midnight to 2 a.m., three nights a week.”

Were there any memorable antics? “I wish I could tell you,” he said with a demurring grin.

Others were a tad more forthcoming. “I get all weepy thinking about all the great times I had to pour myself out of here,” said Barry Tubb, 52, an actor from “Friday Night Lights” who may be best known as Wolfman in “Top Gun.” Tubb had so many fond memories of Raoul’s, he flew in from Marfa, Texas, for the night. “I first came here in 1985 with Kelly McGillis, and we had dinner with Jennifer Beals,” he said. “Wow, it was like all the good things about New York in one room.”

Though not officially an after-hours club, Raoul’s seemed to operate like one at the height of its popularity in the mid-1980s, led by a charismatic headwaiter at the time, Rob Jones. After midnight, Jones was known to descend the circular staircase in Dusty Springfield drag, lip-syncing and leading the crowd in dance that more than once ended with patrons shimmying naked on the bar.

The party ended abruptly when Jones died of AIDS in 1989. In the 1990s, Raoul’s became a hangout for members of the indie film set, with the producer and former Raoul’s waiter Laurence Bender bringing Quentin Tarantino and the “Pulp Fiction” cast to celebrate the movie’s debut at the New York Film Festival. Other regulars of that era included Sarah Jessica Parker, Ethan Hawke and Uma Thurman.

But Serge Raoul did not set out to create a bacchanalian celebrity magnet. Indeed, the genesis of the place was something of a lark.

A colleague of his from French television, Jim Szalapski, took him to an Italian restaurant at 180 Prince St. at the time. They were so taken by the quaint spot that they approached the owner and jokingly said that they had heard that the business was for sale. The owner, who was ready to retire, liked them and sold the restaurant to Serge Raoul for $15,000 with two odd conditions: the owner’s husband and their cat Inky could stay.

Serge Raoul’s parents owned an upscale restaurant back in France, so he and his brother, Guy, decided to open a low-key bistro. “The original idea was to try to create something where people could come, feel at home,” said Guy Raoul, 65, who is still an owner of Raoul’s. “A place to eat with their fingers if they wanted to and just give that nice leisurely atmosphere.”

Like his father, Karim Raoul did not plan to get into the family business, studying filmmaking at the New York University Tisch School of the Arts a few blocks away. But in 1995, he started working weekends there, doing everything including washing dishes, assisting the butcher and waiting tables.

When he graduated, he took up residence in an apartment above the kitchen, and, after a short stint running his own restaurant in Brooklyn and working in film, he returned to Raoul’s after his father’s stroke.

“We come from a long legacy of people who didn’t want anything to do with the restaurant business,” he said, with a knowing smile.

As Raoul’s enters its fifth decade, Karim sees a bright future for the restaurant, even as he pursues filmmaking, directing a documentary about the changes in SoHo. The current chef, David Honeysett, has broadened the menu beyond traditional bistro fare to include seasonal dishes. But the steak au poivre remains firmly in place.

“I think they drug everybody with that steak,” Tubb said. “I think the steak au poivre sauce has some kind of LSD effect on people, and they have to have it. They crave it.”