The Brit plays Panthers leader Fred Hampton in the powerful film and needed to prepare for a series of sequences in which he had to speak like a passionate revolutionary to crowds of followers without losing his voice, so to strengthen his vocal range he tried a little opera therapy.
"I had to condition my vocal chords and engage my diaphragm, because I'd be doing speeches for, like, 12 hours," he tells "Good Morning America". "Like any muscle, you need to get it strong in order for you to sustain that, in order not to do permanent damage to it."
"I also had to study cadence, because Chairman Fred Hampton had a different cadence to when he spoke and when he did speeches and I wanted them to feel different but feel like the same person at the same time."
Meanwhile, in a separate TV interview, the actor revealed he trained himself to become ambidextrous.
The star decided to learn a new skill during the first COVID lockdown in the U.K. last year (20), and impressed himself with his progress.
"I... taught myself to write with my left hand," he explained on Britain's "The Graham Norton Show".
"On the first day it looked like I was writing while the house was being bombed, but to see the progression in six months was amazing."
"It makes you realise that doing stuff you normally do and then doing it a different way challenges the way you do everything."
However, not all of Kaluuya's time was spent picking up useful skills - he also found himself ditching his usual diet as he began to indulge in all of his favourite foods while stuck at home.
"I let go and ate everything!" he laughed.