Hamilton secured a century of wins in dramatic circumstances at Sochi as a late downpour turned the race on its head.
Running in second behind Lando Norris, Hamilton opted to pit for the intermediate tyres, while Norris stayed out on slicks.
The conditions worsened, allowing Hamilton to get into the lead as Norris struggled tip-toed around the track on the wrong tyres.
Reflecting on the achievement, Brawn admits he never thought anyone would topple Michael Schumacher’s tally of 91, but now expects Hamilton to build on his record significantly before he retires.
“It’s a milestone no one thought anyone would ever reach,” Brawn wrote in his post-race column. “Michael’s tally of 91 was so far ahead of what anyone else had ever done at that point that it never seemed conceivable that anyone would get near it. But then Lewis beat it – and now Lewis has 100 wins. There is nothing stopping him.
“Who knows where it’s going to end up? He’s with us for another couple of years at least – and he will win races every year. I don’t think we could predict 200 wins, but I think we could certainly predict 20 more as he’s still massively competitive and motivated. It’s just staggering and congratulations to him, as it’s a centenary that no one ever thought would be achieved.”
Brawn also praised Hamilton and Mercedes for bouncing back from a mistake-filled qualifying session.
“It’s a measure of a world champion in a world championship team, that little glitches – such as Lewis hitting the wall in qualifying – look glaring because you make them so infrequently,” Brawn added.
“Mercedes and Lewis weren’t on it in qualifying, at a track where they were expected to dominate given recent history. Friday practice showed they were much quicker on the long runs. It was all there for them to take advantage. So the fact it didn’t go to plan shows that this is not a slam dunk for them.
“They’re going to have to fight hard all the way to the end if they are going to win the championship.”
Hamilton sits two points clear of Verstappen in the drivers’ championship with seven rounds remaining.