The 29-year-old lowered her own global best by 0.18 seconds at the National Stadium in Tokyo, with compatriot Kare Adenegan in second.
Silver medallist Adenegan, who finished in a time of 17.03, made the stronger start of the two before her dominant team-mate surged clear to once again claim top spot on the podium.
Glory moved Cockroft a step closer to a long-term target of surpassing the 11 Paralympic medals Baroness Tanni Grey-Thompson won between 1992 and 2004.
She can close that gap further in the 800m final on Saturday.
“I honestly didn’t know that time was within me,” said Cockroft. I knew that Kare was going to move out of the blocks, and I had to go with her as best I could.
“She just pulled a good time out of me. It has been coming, it has always been there hiding, it has just taken a few years to show its face.”
Cockroft has established herself as one of her country’s most recognisable Para athletes after bursting on to the scene with two golds at London 2012 and then adding a further three in Rio four years later.
Since returning from Brazil, her profile has been raised further as a presenter on BBC nature programme Countryfile, in addition to an appearance on The Great British Bake Off.
She recently claimed cooking in front of celebrity chef Paul Hollywood was more daunting than competing at the Paralympics but there are no signs of complacency creeping into her day job.
The 12-time world champion lowered her own global records in the 100m, 200m, 400m and 800m at the World Para Athletics Grand Prix in Switzerland in May and resumed her spellbinding form in the Japanese capital.
She arrived as clear favourite as the only competitor to have dipped below 17 seconds this year.
Adenegan appeared to be the biggest threat to the crown and so it proved.
The 20-year-old from Coventry, competing in the adjacent lane, gave her fellow Briton a major scare by flying out of the blocks before ultimately being overhauled as she settled for second spot and a season’s best, which was still significantly slower than her lifetime record of 16.8.
“There was definite panic there,” said Cockroft.
“The 100m, when you’re sitting on that start line, looks so short. She went, and I thought, ‘I haven’t got enough time. I need 120.’
“You just need to get your head down, get your arms moving.”
Australian Robyn Lambird clinched bronze, more than 1.6 seconds behind Adenegan, with another GB athlete, Fabienne Andre, fifth in 19.14.
Scarborough-born Laurence Whiteley and Leeds’ Ellen Buttrick also celebrated gold in their respective rowing events.
Whiteley made it a 30th birthday to remember by topping the PR2 mixed double sculls podium alongside Lauren Rowles, recording a winning time of 8:38.99.
That success at Sea Forest Waterway was swiftly followed by glory in the PR3 mixed coxed four final for Buttrick, Giedre Rakauskaite, James Fox and Ollie Stanhope, plus cox Erin Kennedy.
They finished in 6:49.24, more than 11 seconds ahead of the United States and almost 18 seconds clear of bronze medallists France.
Whiteley and Rowles crossed the line just under five seconds ahead of Dutch duo Annika Van Der Meer and Corne De Koning, with Chinese pair Liu Shuang and Jiang Jijian almost 10.5 seconds off the pace in the bronze medal position.
Whiteley, who has limb deficiency following treatment for bone cancer, had relatively modest celebration plans.
“I might have a birthday muffin,” he said. “We did what we set out to do.
“We have a lot of trust in each other, and we have a lot of confidence in our own abilities.”
Normanton’s Jamie Stead, Rotherham’s Gavin Walker and Stockton-on-Tees’s Jack Smith were a pivotal part of the Great Britain side that claimed a historic first Paralympic medal in wheelchair rugby –storming to gold with a superb 54-49 win over three-time champions the United States.
Spearheaded by 24 tries from Jim Roberts, ParalympicsGB triumphed in Tokyo having led at the end of each quarter.
Wheelchair rugby made its full debut as a medal event at Sydney 2000 after being a demonstration sport at the Atlanta Games four years earlier.
A milestone moment for the country in the mixed gender game came following previous bests of bronze-medal match defeats in 1996, 2004 and 2008.
Jointly captained by Chris Ryan and Gavin Walker, GB had guaranteed a place on the podium on Saturday courtesy of a 55-49 win over hosts Japan.