Cummins entered the fray at 101 for five, with his Kolkata Knight Riders side chasing a target of 162.
The 28-year-old then managed to hammer home an unbeaten 56 off just 15 balls, reaching his half-century in 14 to secure a five-wicket win and equal the record for the fastest 50 in IPL history.
What makes Cummins' record-equaling knock even more impressive is that every other batter was struggling to tame the steep bounce on the rough pitch.
But Cummins was unphased by the conditions and even managed to hit Daniel Sams for 35 in one over.
What's more, the Australian captain showed his all-rounded ability throughout the match, taking two wickets, including that of the in-form Ishan Kishan, to help limit the Mumbai Indians to 161/4.
Following the match, former India head coach Ravi Shastri joked that Cummins ruined what was turning into a dramatic clash.
With just five wickets in hand and needing 61 runs from 41 deliveries, the Wednesday showdown looked to be turning into a tense classic.
However, within an over, Cummins put on a clinical performance to put an end to any question marks over the winner.
Shastri said, ""It's like someone walking past him should tell him 'Well played Pat. Thanks for spoiling a really good game of cricket.' He spoiled a very good game of cricket!
"It was unreal. 35 runs in an over. You have to start thinking when did you see a match like this where the other team had the upper hand to an extent and then it goes to maybe 60-40 for Mumbai Indians.
"Come the next over, it's over. It's been a long time since I've seen a match like this and I have seen a lot of cricket," he said about KKR's chase.
The result sent KKR top of the IPL standings with three wins in their first four matches, their next comes against the Delhi Capitals on Sunday.