Chisora floored Williams twice in the second round to earn victory.
Derek Chisora won the British heavyweight title after a fine second-round victory over Danny Williams at Upton Park on Saturday.
Chisora wobbled Williams in the second round with a right-hand uppercut and later floored him with a chopping left.
And unbeaten Chisora finished the job soon after, flooring Williams with a right over the top to end the fight.
Also on Saturday there were victories for unbeaten trio Billy Joe Saunders, James DeGale and Frankie Gavin.
Williams, 36, vowed before Saturday's fight that he would retire after his meeting with Chisora and from the first bell the 'Brixton Bomber' was on the back foot.
Chisora, 26, used his jab to decent effect and looked the busier boxer from the off. He had Williams in trouble early in the second with a heavy uppercut which had his opponent hanging on.
Several heavy shots followed before a fine left sent Williams into the ropes and on to the canvas.
From that point Williams was always struggling and it was a right to the top of the 36-year-old's head that floored the champion once again, with referee Howard John Foster stopping the fight.
"I want to thank all my team for this, now we're ready to go," said Chisora, who took his record to 13 victories with eight knockouts.
Promoter Frank Warren added: "I'm very excited about Derek, he's got a lot of talent, great self-belief and if he can stay focused and channel it I think he can go all the way."
Chisora is likely to box Commonwealth title-holder Sam Sexton next, but for Williams, his 51-fight career looks over.
And Warren believes Williams should now hang up his gloves.
"Danny's been a great warrior over the years," Warren told BBC Sport.
"I hope he now finally retires and if he doesn't retire I hope the [British Boxing] Board stop him from fighting because he didn't look good after the fight."
DeGale's victory over Sam Horton saw him win the fringe WBA super-middleweight international belt and the 2008 Olympic gold medallist soon set himself on achieving bigger things following his classy victory.
"I felt great in there and I'm glad Sam took me five rounds as I need them," said DeGale.
"When I hit him and hurt him I thought, 'let's get this done'.
"I'm a man on a mission and by the end of the year I want to a British or Commonwealth champion.
"By the end of 2012 I want to be fighting for a world title at the Emirates or at Wembley. The future's bright, the future's 'Chunky'."
The 24-year-old landed some big shots in the first round, abandoning technique and defence in search of the big punches which to his credit Horton took well.
Londoner DeGale rocked Horton with a left over the top but also got caught himself by his 24-year-old opponent.
But a fierce left in the latter stages of the second round floored Horton who managed to hold on until the end of the round.
DeGale caught Horton with several heavy uppercuts in the third and things got worse for him when he was deducted a point a round later for holding.
And DeGale finished the job in the fifth with a stunning right-uppercut, left hook, right-jab combination which floored Horton and saw his corner throw in the towel.
Elsewhere, light-welterweight Gavin earned his seventh win and sixth stoppage with a fine first-round victory over Gavin Tait.
Gavin was cut above the right eye in an entertaining first round which saw the fight stopped after Tait received too much punishment from the 24-year-old.
"I felt I was hitting him hard and that the body shots were hurting him," said Gavin.
"I'm progressing brilliantly and I hope for a British title shot by the end of the year."
And super-middleweight Saunders, boxing for the sixth time, earned his third consecutive points win with a tough victory over Andy Butlin.
The former amateur star was fighting for the first time since breaking his left hand at the end of 2009. And Saunders admitted to his corner before the start of the final round that he felt a "twinge" in his left hand causing concern that the 20-year-old had suffered the same injury.
Saunders cut Butlin in the final round and eventually earned a 60-55 points victory.