Conor Benn angrily knocked out Steve Jamoye in the fourth round at The O2 in London on Saturday night.
Benn was deducted a point by the referee for a low blow and responded by upping the ante, and winning his welterweight fight moments later.
He cracked Jamoye with two consecutive right hands, which badly hurt him, then sent him flying to the canvas with a left hook.
Unbeaten Benn had spent the first few rounds investing in body shots but his left hand to the ribs was sometimes accurate, and sometimes strayed low, leading to his punishment from referee Steve Gray.
Benn celebrated his 16th consecutive victory with his father Nigel Benn, the British boxing legend who will fight next month for the first time in 23 years at the age of 55.
Benn picked up the WBA 'continental' title by emphatically stopping his Belgian visitor.
The 23-year-old reacted afterwards at having a point deducted: "I was angry, it's not my fault he's short! I told the referee: 'why did you do that?'.
"He's done 10 rounds nine times, I've done 10 rounds once.
"This is my 16th fight and 14 of them have touched the canvas. I will catch you, at some stage."
Promoter Eddie Hearn said: "He is improving so much. He works so hard. He will be a great fighter.
"You won't see him in nightclubs, you won't see him abusing his lifestyle. He's in the gym with his dad - you can see Nigel Benn in this kid.
"2020 will be a massive year for him."
Watch repeats of the WBSS final and Chisora vs Price on Sky Sports Box Office, from 9am and 3pm on Sunday. Book it via your Sky remote or book it online here.