Elsewhere, Richard Linklater's Boyhood won the Best Film and Best Director awards at the British Academy Film Awards (BAFTAs), held at the Royal Opera House in London, England.
The 54-year-old director, whose previous work includes Dazed and Confused, overcame competition from Wes Anderson (Grand Budapest Hotel), Damian Chazelle (Whiplash), Alejandro Gonzalez Inarritu (Birdman), and James Marsh (The Theory of Everything) to claim the prestigious award.
The prize was collected on behalf of Linklater by Boyhood star Ethan Hawke, who said: "I've made eight films with him and he's a great friend. No one loves cinema more than Richard."
Hawke joked that the director will be annoyed that he didn't attend the event at the Royal Opera House in London to collect the award in person, as he's at the Directors' Guild Awards in Los Angeles.
The actor quipped: "Like Wes Anderson, he was hijacked at the Director's Guild of America awards and he will be p***** off he's not here tonight.
"The easy part was making the movie, the hard part was giving it to the world."
Boyhood was filmed over the course of 12 years—from 2002 to 2014—and tells the story of a young boy in Texas who grows up with divorced parents.
FIVE AWARDS. The Grand Budapest Hotel, on the other hand, claimed five prizes in total.
The Wes Anderson-directed movie won Original Screenplay, Original Music, Production Design, Costume Design, and Make Up & Hair.
Anderson was unable to collect the prize for Best Original Screenplay, leaving Ralph Fiennes to claim it on his behalf.
The actor read out a message from Anderson, saying: "I have a letter from Wes it goes like this: if Ralph Fiennes is reading this speech it must mean I have won a BAFTA for our screenplay in absentia.
"I was already unhappy to miss this event but now I'm really angry and resentful that I am not there, and I'm furious.
"I blame the Directors' Guild of America, for requiring my presence in Los Angeles where most likely I have already failed to win a different prize.
"I extend my many thanks to the British Academy, of which I am a member in good standing and I look forward to very eagerly getting a hold of this award physically in my own hands as quickly as Fed-Ex can possibly deliver it to me."
BEST ACTOR. Meanwhile, The Theory of Everything won three awards; including Outstanding British Film, while the movie's star Eddie Redmayne claimed the Leading Actor award.
The 33-year-old Brit, who starred as Professor Stephen Hawking, won the sought-after award ahead of Benedict Cumberbatch (The Imitation Game), Ralph Fiennes (The Grand Budapest Hotel), Jake Gyllenhaal (Nightcrawler), and Michael Keaton (Birdman).
After collecting his award, he said: "I was at the BAFTAs three years ago and I had food poisoning—I redecorated the corridor of the Royal Opera House.
"That was one of the worst nights of my life—this is one of the best nights of my life."
Redmayne dedicated his award to his own family for "their amazing faith", as well as his co-stars—including Felicity Jones—and the family of Stephen Hawking.
Of the Hawking family, he said: "I want to thank them for their trust, their generosity and their kindness.
"And for reminding me of the great strength that comes from having the will to live a full and passionate life."
Redmayne's BAFTA win comes after he won the Golden Globe Award for Best Actor - Motion Picture Drama in January.
BEST ACTRESS. American actress Julianne Moore won the Leading Actress award for Still Alice, beating Reese Witherspoon, Amy Adams, Rosamund Pike, and Felicity Jones to the prestigious prize.
The 54-year-old actress won the award for her performance as Dr. Alice Howland—a renowned linguistics professor at Columbia University in the US.
When she collected her award, Moore thanked "everybody in the Alzheimer's community who were so generous with their time and telling me their experiences."
The movie—which also features Alec Baldwin, Kristen Stewart, and Kate Bosworth—follows Moore's on-screen character's battle against Alzheimer's disease.
The drama film, which is written and directed by Richard Glatzer and Wash Westmoreland, is based on the 2007 best-selling novel of the same name by Lisa Genova.
Moore—who has also written a successful series of children's books—won the Golden Globe Award for Best Actress in a Motion Picture - Drama in January and has also received her fifth Oscar nomination for her performance in the film.
WINNERS' LIST. Winners from the British Academy Film Awards 2015:
Best Film: Boyhood
Leading Actor: Eddie Redmayne - The Theory of Everything
Leading Actress: Julianne Moore - Still Alice
Best Director: Richard Linklater - Boyhood
Supporting Actor: J.K. Simmons - Whiplash
Supporting Actress: Patricia Arquette - Boyhood
EE Rising Star: Jack O'Connell
Original Screenplay: The Grand Budapest Hotel - Wes Anderson
Adapted Screenplay: The Theory of Everything
British Short Animation: The Bigger Picture
Make-up and Hair: The Grand Budapest Hotel
British Short Film: Boogaloo And Graham
Original Music: The Grand Budapest Hotel
Outstanding British Film: The Theory Of Everything
Outstanding Debut by a British Writer, Director or Producer: Stephen Beresford, David Livingstone - Pride
Production Design: The Grand Budapest Hotel
Fellowship: Mike Leigh
Special Visual Effects: Interstellar
Film Not in the English Language: Ida
Animated Film: The Lego Movie