Gary Oldman came away with the Best Actor award for his portrayal of Winston Churchill in a night of success for British stars at the Oscars.
The Shape Of Water picked up four of the 13 Oscars it was nominated for, including best director for Guillermo del Toro and the night's biggest prize, best picture.
Oldman, 59, thanked his 98-year-old mother as he landed his first ever Oscar for his role in war-time drama Darkest Hour.
The 59-year-old, who narrowly missed out on a gong for his performance as George Smiley in 2011's Tinker Tailor Soldier Spy, said: "I say to my mother, thank you for your love and support, put the kettle on - I'm bringing Oscar home."
The main awards on the night went to:
- Best Picture - The Shape of Water
- Best Actor - Gary Oldman (The Darkest Hour)
- Best Actress - Frances McDormand (Three Billboards Outside Ebbing, Missouri)
- Best Supporting Actor - Sam Rockwell (Three Billboards Outside Ebbing, Missouri)
- Best Supporting Actress - Allison Janney (I, Tonya)
There was also success for British war film Dunkirk, which got three nods for Sound Editing, Sound Mixing and Film Editing.
British cinematographer Roger Deakins won his first Oscar for work on Blade Runner 2049 - after 14 past nominations.
Elsewhere, Three Billboards Outside Ebbing, Missouri earned the awards for Best Actress and Supporting Actor.
The defining moment of the evening was Frances McDormand calling on every female Oscar nominee in the room to stand.
She called on industry bosses to "look around" and fund more female-lead projects.
At the end of her monologue she said: "I have two words to leave with you tonight, ladies and gentlemen, inclusion rider."
The clause can be used by bigger name actors and actresses, who have the power to negotiate their contracts, to ensure that cast and crews are representative of minority groups.
The success continued for British performers when Hollyoaks stars Chris Overton and Rachel Shenton both picked up a gong.
Their feature The Silent Child, which follows the life of a deaf girl, took the prize for best live action short film.
Shenton, who played Mitzeee Minniver in the Channel 4 soap, delivered her acceptance speech in sign language in tribute to the film's six-year-old lead actress.
- Kimmel's call to Hollywood to 'clean up its act'
The awards came on an evening when several stars showed their support for victims of sexual harassment.
A number of A-listers arrived at the ceremony wearing "Time's Up" badges.
Host Jimmy Kimmel then called on Hollywood to clean up its act in the wake of the Harvey Weinstein scandal, telling the audience "not to let bad behaviour slide".
Later Ashley Judd, one of the first actresses to speak out about Weinstein, took to the stage to encourage victims of harassment to come forward.
- The Shape of Water soaks up awards
The Shape Of Water had a highly successful night being named Best Picture.
Warren Beatty and Faye Dunaway returned to the Oscars stage to present the final award of the night a year after the best picture fiasco when they mistakenly announced La La Land as the winner rather than Moonlight.
Guillermo del Toro's film scooped three other Oscars, including one for himself as Best Director.
With 13 nominations, it also won Original Score and Production Design.
- Rockwell's tribute to Philip Seymour Hoffman
Sam Rockwell took Best Supporting Actor for his portrayal of Jason Dixon in Three Billboards Outside Ebbing, Missouri.
Co-star Frances McDormand took Best Actress for her role in the same film.
Rockwell, 49, dedicated his award to late actor Philip Seymour Hoffman, who died in 2014.
He said: "He was very close to me and he was an inspiration to all of my peers.
"Everyone who is in my age range, Phil Hoffman was the guy."
Meanwhile Allison Janney won best supporting actress for her performance alongside Margot Robbie in I, Tonya.
Janney fought off competition from Laurie Metcalf in Lady Bird.
- 'It feels better than winning at basketball'
Kobe Bryant is one of basketball's biggest names having won the NBA championship five times.
But this time he turned from success on the court to success at the Oscars as his film Dear Basketball took a nod for animated short film.
He said: "I feel better than winning the championship, I swear I do.
"Growing up as a kid I dreamed of winning championships, working really hard to make that dream come true, then to have something like this seemingly come out of left field..."
FULL LIST OF WINNERS:
- Actor - Gary Oldman (The Darkest Hour)
- Actress - Frances McDormand (Three Billboards Outside Ebbing, Missouri)
- Supporting Actor - Sam Rockwell (Three Billboards Outside Ebbing, Missouri)
- Supporting Actress - Allison Janney (I, Tonya)
- Best Director - Guillermo del Toro (The Shape of Water)
- Makeup and Hairstyling - Darkest Hour
- Costume Design - Phantom Thread (Mark Bridges)
- Documentary Feature - Icarus
- Sound Editing - Dunkirk (Richard King and Alex Gibson)
- Sound Mixing - Dunkirk (Gregg Landaker, Gary Rizzo, Mark Weingarten)
- Production Design - The Shape of Water
- Foreign Language Film - A Fantastic Woman (Chile)
- Animated Short Film - Dear Basketball
- Animated Feature - Coco
- Visual Effects - Blade Runner 2049
- Film Editing - Dunkirk
- Documentary Short Subject - Heaven Is A Traffic Jam On The 405
- Live Action Short Film - The Silent Child
- Adapted Screenplay - Call Me By Your Name
- Original Screenplay - Get Out
- Cinematography - Blade Runner 2049
- Original Score - The Shape of Water
- Original Song - Remember Me (Coco)