The 20-year-old needed less than three minutes to dispatch the former world title challenger, flooring him with a right hook before the referee stepped in.
The win extends Itauma’s unbeaten professional record to 13 victories, 11 of them inside the distance.
Whyte, 37, was returning to the ring for the first time since losing to Tyson Fury in 2022.
"I will fight anyone they put in front of me," Itauma later said, though he ruled out calling for a bout with unified champ Oleksandr Usyk.
"I don't believe I deserve the opportunity," he added.
Promoter Frank Warren hailed the young prospect as “the most unbelievable finisher”, with Itauma’s latest win extending his run of early stoppages since his pro debut in 2023.
Earlier, Liverpudlian Nick Ball retained his WBA featherweight title with a unanimous points victory over Sam Goodman, while David Adeleye lost to Filip Hrgovic.