A few hundred people, including scores of celebrities, Hollywood executives and agents, filled the Directors Guild Theatre on Sunset Boulevard to share laughs, tears and anecdotes about the Oscar-winning performer, whose marvellously rumpled looks and slouchy, grouchy persona made him one of America's best-loved comic film stars.
Matthau died on July 1 of a heart attack in Santa Monica at the age of 79.
"He was my best friend. I love him, I always will. And I will miss him," said Matthau's off-screen pal and best-known co-star, Jack Lemmon. Then, choking back tears, Lemmon added: "One thing is a constant. Whenever I was with Walter, whether it was in a film or personally, it was always a magic time."
Actress Diane Keaton, who directed and co-starred with Matthau in his last picture, "Hanging Up", said he possessed "an ironic dignity."
"His face was the best face I've ever laid eyes on, not handsome but magnificent," she said.
"Acted with every organ''
Playwright-producer Neil Simon, who wrote "The Odd Couple" with Matthau in mind for the part of cranky, slovenly sportswriter Oscar Madison, said Matthau was great because he "acted with every organ in his body."
"He was the easiest person for me to write for because even when I wasn't funny, he was," Simon said. "He was brilliantly funny, extraordinarily funny, but he wasn't a comic. He was first and foremost an actor."
Also saluting the New York-born actor during the service were veteran comedian Red Buttons, CNN celebrity-interviewer Larry King and actress Lauren Bacall, who read a tribute from Matthau's widow, Carol Marcus, saying, "We had lots of fights and perfect love."
Among other celebrities on hand were Sophia Loren, Gregory Peck, Karl Malden, Carol Burnett, Norman Lear, Carl Reiner, Richard Lewis, Daryl Hannah, Tom Poston, bandleader-clarinettist Artie Shaw and Richard Benjamin, who played Matthau's nephew and agent in "The Sunshine Boys."
Perhaps the funniest story of the day was recounted by Matthau's rabbi, Jerry Cutler, who remembered having lunch with the actor, ordering a spinach salad and then not being able to eat it because the salad was topped with bacon bits.
Matthau, he said, picked up the salad and began going from table to table pretending to auction it off to the highest bidder, asking, "How much for a spinach salad blessed by Walter Matthau's rabbi?''
Hot dogs and fortune cookies
The service - for which the actor's son, producer Charlie Matthau, was host - also included a montage of the star's work. Afterward, guests dined on snacks that included Nathan's Famous kosher hot dogs - one of Matthau's favourite foods - and fortune cookies with slips of paper bearing the name of one of Matthau's movies, the part he played and a line or two of dialogue.
Matthau won his Academy Award for best supporting actor for his role in the 1966 Billy Wilder hit "Fortune Cookie".
On the back of the programme for the service, in a nod to Matthau's legendary weakness for gambling, was his pre-season estimate of every National Football League team's chance of winning the Super Bowl XXXV. He had the St. Louis Rams as the 3-to-1 favourite.
Another glimpse of the man came when Lemmon remembered how Matthau had exercised his wit even after taking a bad spill on the set of their 1981 movie "Buddy, Buddy". The accident left Matthau splayed on the floor with a broken collarbone, moaning over and over, "I'm going to die", he recalled.
Not knowing what else to do, Lemmon took off his jacket and carefully slipped it under his friend's head, asking, "Are you comfortable?" To which the reply came: "I make a living.''
"Even though he thought he was dying, he wasn't going to lose that straight line," he said.
