The former New Zealand captain hit England paceman James Anderson through midwicket for four with the fourth ball of the morning at the Basin Reserve to pass Taylor's previous record of 7,683 runs.
By tea, Williamson had chalked up his 26th century in tests to give the hosts some hope of pulling off an unlikely win after they were asked to follow on.
As always, the mild-mannered 32-year-old from Tauranga kept the emotions in check, barely acknowledging the warm applause from the crowd after taking the runs record.
Later in the day, after being caught behind for 132 off Harry Brook's part-time medium pace, Williamson showed he has lost none of his discomfort talking about his achievements.
"It's not something that I've sort of thought about a whole lot but it is an honour," he told reporters of the record.
"I look at that list and I've admired all of those players over the years, whether that's watching from afar growing up or playing alongside a number of them as well.
"It's not a focus point, but it's special to be amongst that company."
A nation of five million, New Zealand has produced a slew of brilliant cricketers over the decades but none have made their mark with the bat quite like Williamson.
Taylor's tally of runs came from 112 matches, while Williamson, now on 7,787 runs at an average of 53.33, is playing his 92nd test.
Former teammate Taylor, who retired last year, was quick to congratulate him.
"This achievement is a testament to your hard work and dedication to test cricket, of which I was privy to for a number of years," he said.
"Here’s to many more."
Williamson managed only 10 runs across his three previous innings of the series against England but answered the team's call for a big score on Monday.
He batted superbly through a 282-ball knock, anchoring partnerships with Henry Nicholls (29), Daryl Mitchell (54) and Tom Blundell (90) in New Zealand's second innings of 483.
Tim Southee's side will bid to record just the fourth win in history by a team asked to follow on.
Should they pull it off, they will have their quiet talisman Williamson to thank for setting up the chance.
"I think we can ask a number of questions coming in to day five," he said.
"It's always exciting when all three results are on the table."
