Although Elton is a veteran of stage productions, Maybe Baby, adapted from his novel, Inconceivable, marks the comedian's debut as a film director.
Actress Joely Richardson, wearing a shimmering gold dress, stole the show from a celebrity throng of guests which included the Prince of Wales, singer George Michael and comedian Rik Mayall.
Richardson stars with Hugh Laurie in the film which is about trying for a baby through infertility treatment.
Although Elton is a veteran of stage productions, Maybe Baby, adapted from his novel, Inconceivable, marks the comedian's debut as a film director.
Prince Charles gave the event - at the Odeon Leicester Square - the royal seal of approval and bantered with the actors.
Richardson said the prince jovially asked her: "It's not too rude is it?"
"I said, 'yes', then he asked, 'with lots of laughter?', so I said, 'absolutely'."
The actress was accompanied by her young daughter Daisy who handed the royal visitor a programme. The prince asked her: "Have you seen it?"
But director Elton put his finger in front of his lips and told her: "Ssshhh, it's a 15 certificate."
Richardson's mother, Vanessa Redgrave, and her aunt Lynn made it three generations of the famous acting clan at the premiere.
Other guests at the screening included actress Emma Thompson, who showed off a new cropped and bleached hairstyle.
She said she had decided to opt for a radical change before shaving it all off in readiness for playing someone who dies of cancer in September.
Also at the event, in aid of the Prince's Trust, were stars of BBC sitcom The Royle Family - Caroline Aherne, Ricky Tomlinson, Sue Johnson, Craig Cash and Ralf Little.
Stars from the field of comedy included Rowan Atkinson, who appears in the
film, Steve Coogan, Charlie Higson from The Fast Show and Rik Mayall.
George Michael waved to the crowd as he arrived but slipped into the cinema behind other arriving guests to avoid photographers and reporters.
The novel on which the £3 million film is based was inspired by Ben Elton's own struggle to have a child, which resulted in him and his wife Sophie turning to IVF treatment.