Whittaker broke down and thanked his dad after producing a tight split decision win over Brazil's Keno Machado.
The light-heavyweight edged the verdict on three of the five judges' cards and let his emotions run riot as he paid tribute to the man who has supported him through his amateur boxing ascent.
Whittaker said: "I was crying. I was trying to keep as calm as I could but I couldn't really help it.
"That win was for him (my dad). He works mornings at 5am and his work has given him the courtesy of watching me. He hasn't slept all night and he has been giving me tactics, trying to keep me calm."
Pat McCormack also enjoyed an explosive win over Uzbek Bobo Baturov, who did enough to earn the verdict from one of the five judges.
McCormack, the world number one at welterweight, sustained a cut during the fight but he shrugged off its importance ahead of his semi-final bout against Ireland's Declan Walsh.
"I got cut in the last round, so I just tried to stay out of his way to make sure I'm boxing in the next round," said McCormack.
"But it should be all right, I'll just get it super-glued. I've got a day's rest, and then I'll be ready to go on Sunday."
Caroline Dubois, the younger sister of heavyweight boxer Daniel Dubois, moved closer to a medal after beating Rashida Ellis of the US to advance in the women's lightweight class.