With the series already secure after last week's victory in Melbourne, Australia's openers gave the hosts the best possible start to their quest for a 3-0 series sweep.
Warner, playing on his home ground just a few hundred metres from where he was born, reached the hundred mark from 78 balls in 118 minutes to become the fifth batsman to notch up a century before lunch on the first day of a test.
The left-hander was unable to add to his tally of 17 fours before being caught behind off Wahab Riaz for 113 soon after lunch but Renshaw, playing his fourth test, proved more than capable of taking up the mantle.
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The 20-year-old, initially circumspect where Warner was aggressive, was knocked to the floor by a sickening blow to his helmet grille from a Mohammad Amir bouncer on 91 but got up to complete his century from 201 balls with eight fours.
When stumps were drawn, Renshaw was unbeaten on 167 with Peter Handscomb on 40 not out alongside him in a partnership of 121.
Usman Khawaja (13), Warner and Australia skipper Steve Smith (24) all fell to catches behind the wickets, the last a spectacular take by Sarfraz Ahmed off spinner Yasir Shah.
Otherwise, it was a day to forget for the tourists as Warner and Renshaw ran rampant on a good wicket after Australia had won the toss and chosen to bat.
As pugnacious as ever, Warner barely hit a false note in his 95-ball innings, hitting the second ball he faced for four and not letting up until he had run the three runs that secured his 18th test century.
No batsman had ever hit a century in the opening session of a test match in Australia and only compatriots Victor Trumper, Charles Macartney and Don Bradman as well as Pakistan's Majid Khan had done it elsewhere.
"It's a honour and privilege to be amongst the greats of the game," Warner said.
"It wasn't something in the back of my mind to go out and score a 100 in a session. It was about going out there with intent and batting positive."
Warner also bettered his own record for the fastest test century at the SCG, having taken 82 balls to reach the milestone against West Indies here last year.
Renshaw had scored only 25 runs at lunch and stuck with his cautious approach through the second session and into the third, spending seven overs in the 90s before a single gave him his century.
The crowd gave him the standing ovation his application deserved and continued to roar their approval at the 10 boundaries that followed as the Queenslander finally threw off the shackles a little.
He survived an lbw scare off the bowling of leg-spinner Yasir on 137 - the technology showed a clear edge off the bat - and received another big ovation as he departed the field unbeaten at close of play.
Pakistan paceman Wahab, who took 2-63, did not try to put a gloss on a disappointing day.
"I think as a bowling unit, we have really let down our team," he said.
(Editing by Greg Stutchbury and Sudipto Ganguly)
