The historical drama, directed by Shaka King, tells the story of the betrayal of Illinois Black Panthers chairman Fred Hampton, played by Kaluuya.
Competing against Kaluuya for the award was Lakeith Stanfield, who starred in Judas as Bill O’Neal, the FBI informant who betrayed Hampton.
“Thank you God. I couldn’t be here without your guidance and protection,” said Kaluuya in his acceptance speech.
He also praised Hampton, saying: “What a man, how blessed we are we lived in a lifetime where he existed.
“I share this honour with the gift that is Lakeith Stanfield, the light that is Dominique Fishback... It’s so incredible to look around you and be inspired not just by what they do but who they are.”
Kaluuya also thanked other collaborators and his family, at one point remarking that everyone should “celebrate life”, joking: “Mum and dad, they had sex. It’s amazing! I’m here!”
The other nominees for Best Supporting Actor were Sacha Baron Cohen (for The Trial of the Chicago 7), Leslie Odom Jr (for One Night in Miami…) and Paul Raci (for Sound of Metal).
The 93rd Academy Awards took place on 25 April, having been delayed for two months due to the ongoing pandemic.
The ceremony was held primarily in Los Angeles’s famed Union Station, with nominees from outside of the US attending the event via international hubs.
Among the films competing for top awards were Chloé Zhao’s life-on-the-fringes drama Nomadland, Emerald Fennell’s feminist revenge satire Promising Young Woman, and the August Wilson play adaptation Ma Rainey’s Black Bottom.
Going into the night, David Fincher’s Mank had the most nominations (10), including for Best Director, Best Actor for Gary Oldman and Best Supporting Actress for Amanda Seyfried.
The Father, Minari, Nomadland, Sound of Metal and The Trial of the Chicago 7 all had six nods apiece.