Harrison Ford, Carrie Fisher and Hamill are set to return in the new Star Wars instalment alongside a host of newcomers, while Daniels will reprise his role as C3PO.
After the cast for Episode VII was unveiled Hamill tweeted: "Finally I can officially say: I'M IN!!! #StarWars #StarWarsEpVII"
Daniels apologised to fans for keeping the news a secret, tweeting: "Apologies to all those fans at Calgary Expo who asked me about Ep VII. Keeping the secret in front of y'all was the hardest act I ever did.
Months of speculation about the new film finally ended yesterday when the cast was announced.
Ford (Han Solo), Fisher (Princess Leia), and Hamill (Luke Skywalker) will return to the movie.
Other original stars will include Daniels (C-3PO), Peter Mayhew (Chewbacca) and Kenny Baker (R2-D2) in the new film.
Newcomers include British actor John Boyega, who starred in sci-fi London gang film Attack The Block, and Inside Llewyn Davis co-stars Adam Driver and Oscar Isaac.
Boyega tweeted: "Honoured to join this amazing universe and thank you for all the support ....May the force be with you #SWVII."
The cast will also include little-known Brit Daisy Ridley, whose credits include a role in TV drama Mr Selfridge, rising Irish star Domhnall Gleeson, who appeared in Harry Potter, and veteran Minority Report actor Max von Sydow.
Ridley tweeted: "Overwhelmed by all the support. This is the greatest day of my life. I'm told I can't say who I'm playing yet, but it's exciting!"
Andy Serkis will be joining one global franchise from another, having captivated audiences in the role of Gollum in The Lord Of The Rings and The Hobbit.
Director JJ Abrams said: "We are so excited to finally share the cast of Star Wars: Episode VII.
"It is both thrilling and surreal to watch the beloved original cast and these brilliant new performers come together to bring this world to life, once again.
"We start shooting in a couple of weeks, and everyone is doing their best to make the fans proud."
The news was announced on StarWars.com, and featured a photograph of the first read-through.
The droid R2-D2 was the first confirmed character returning to the story when filming begins at Pinewood Studios in Buckinghamshire, famously the home of James Bond films for many years.
The hotly anticipated film is due to begin filming in the UK next month.
The new film is set to be released in December of next year.
The first Star Wars film was released in 1977.