The pop icon and Tom were at a breakfast in Santa Monica on Tuesday to personally tout the 'Rocketman' film.
Elton recently said he and the British actor "get on like a house on fire".
Speaking on 'The Graham Norton Show', he said: "I've spent a lot of time with Tom already... We are very much alike - you wouldn't think so and certainly not physically.
"I wanted a serious actor and I'm so thrilled he is doing it," Elton added.
Elton will be re-recording a number of his greatest hits to fit in with the emotion of the film, which will begin filming in autumn 2014.
Focus Features CEO Peter Schlessel said in a statement when the casting was announced: "Tom is quickly becoming known as one of the world's most versatile actors, and like others at the top of their craft, he has proven his ability to transform himself completely into the character or subject found in the material.
"We are confident that Tom will embody the physicality and spirit of Sir Elton. This, in conjunction with the creative team led by Michael and Rocket Pictures, will provide the foundation for something that will be a unique cinematic event."