The performer won Best Supporting Actor for his role as real-life activist Fred Hampton in "Judas and the Black Messiah." The prize was presented by 2020 Best Supporting Actress winner Laura Dern.
"Thank you so much for pouring into me," Kaluuya said about his mom during his acceptance speech. "It's so hard to make a film, and make a film about a man like this."
In thanking his co-stars, Kaluuya continued, "I share this honor with the gift that is Lakeith Stanfield, the light that is Dominique Fishback."
The "Widows" actor said about Hampton, "What a man. How blessed we are that we lived in a lifetime where he existed."
But things got particularly eyebrow-raising when Kaluuya went on to mention his mom and dad having sex, and the camera showed his mom in the audience, who appeared baffled at what her son was saying.
"It's incredible," the actor said. "My mom met my dad, they had sex, it's amazing. Do you know what I'm saying? I'm here, do you know what I mean? I'm so happy to be alive, so I'm going to celebrate that tonight."
Also nominated were Sacha Baron Cohen ("The Trial of the Chicago 7"), Leslie Odom Jr. ("One Night in Miami..."), Paul Raci ("Sound of Metal") and Lakeith Stanfield ("Judas and the Black Messiah").
Kaluuya, who was a Best Actor nominee for 2017's "Get Out," has been the key front-runner throughout awards season for his role as chairman of the Black Panther Party's Illinois chapter.
During his Golden Globes acceptance speech in February, Kaluuya said, "The great Nipsey Hussle says, 'We are here to give until we are empty,' and I gave everything. I couldn't give it to a more noble man – that's chairman Fred Hampton – and I hope generations after this can see how brilliantly he fought, how brilliantly he spoke and how brilliantly he loved. He taught me about myself, made me grow as a man, and I appreciate it with all my heart."
The star continued at the time, "And I hope people – there's a lot of information about how he died, but I hope you people out there will grow and learn about how incredibly he lived. Thank you so much for this honor."
Brad Pitt was the 2020 winner in the category for his role in Quentin Tarantino's "Once Upon a Time in Hollywood," providing his first-ever career Oscar.