The world number 49 from Mumbai made his perfect break in the third frame of his last 32 match against Stephen Maguire at the European Tour event, trailing 2-0 at the time.
It's the first 147 since Ronnie O'Sullivan's at the Welsh Open in March, and the 106th in snooker history.
Mehta, who was runner-up to Ding Junhui at the inaugural Indian Open last season, will win £1,500 from the rolling 147 prize pot for European Tour events, as long as the break is not equalled.
The break was refereed by local German official Luise Kraatz, who was working at a professional event for the first time and taking charge of only her third match.
"It's an amazing feeling," said Mehta. "The balls opened up and I knew it was an opportunity by the time I was on 32. I've only made one 147 in practice and one in a match in India. I hoped one day I would be lucky enough to make one in a pro event and today it happened out of the blue."
Glasgow's Maguire eventually won the match 4-2.
Defending champion Ronnie O'Sullivan, playing his first tournament of the season, strolled into the last 16, conceding just one frame in three matches. He beat Noppon Saengkham 4-0, Robbie Williams 4-0 and Barry Hawkins 4-1. The Rocket's top breaks of the day were 114, 105 and 101.
Judd Trump was hauled back from 3-0 to 3-3 by amateur Mitchell Travis in the last 32 but recovered to win the decider with a break of 108.
Xiao Guodong edged out Jamie Cope 4-3 with a run of 77 in the decider, while Rob Milkins made 77 and 55 in the last two frames to beat Michael White 4-3.
Alan McManus saw off Scott Donaldson 4-1 while Mark Allen beat Luca Brecel 4-2 with a top break of 81. China's Tian Pengfei made 120 and 70 in the last two frames to beat Mike Dunn 4-3.
