The TV star and singer shared the news of her son's arrival on Instagram, telling followers they are "all in love".
"Our baby boy is here! We’re all in love over here... and exhausted lol!
"Thank you @essence for this lovely announcement."
Tatyana is best known for her role as Ashley Banks on the NBC sitcom The Fresh Prince of Bel-Air, which ran from 1990 to 1996 and also starred Will Smith in his breakout role.
Tatyana announced she was expecting baby number two on Instagram in April.
"I was on a work trip recently and I thought it was about time I captured my baby bump," she wrote.
"We're so excited! They say every pregnancy is different and they ain't lying. Phew! I'm exhausted this go round, swirling with emotion and starving, like constantly. Feeling very blessed. #BabyRasberry."
Congratulations to family!