Gill slammed 101 off just 58 balls with the help of 13 fours and one six, and added 147 runs for the second wicket with Sai Sudharsan (47 off 36 balls), to power GT to 188 for nine despite a late comeback by Sunrisers Hyderabad's Bhuvneshwar Kumar (5/30).
With the bat, SRH were never in the hunt as they kept losing wickets at regular intervals to be restricted to 154 for nine.
Heinrich Klaasen (66 off 44) played a lone hand for SRH, while Mohammed Shami (4/21) and Mohit Sharma (4/28) picked up four wickets apiece to shine with the ball for GT.
SRH were off to a disastrous start, losing the wickets of Anmolpreet Singh, Abhishek Sharma and Rahul Tripathi inside the third over, with the scoreboard reading just 12.
It became worse for SRH in their must-win game as Shami picked up his third wicket in the form of rival skipper Aiden Markram an over later, and then, Mohit dismissed Sanvir Singh and Abdul Samad in the seventh over to reduce the visitors to 49 for six.
This season's campaign was as good as over for SRH as Marco Jansen became Mohit's third victim in the ninth over.
Reeling at 59 for seven, SRH finally managed a partnership through Klaasen and Bhuvneshwar (27), the duo adding 68 runs for the eighth wicket.
Earlier, sent into bat GT suffered an early blow as they lost Wriddhiman Saha for a duck in the third ball of the innings, nicking one to Abhishek Sharma at second slip.
After a sedate start, GT broke the shackles in the third over with Gill and Sudharsan hitting Bhuvneshwar for three exquisite boundaries to pick up 15 runs.
Having found his touch, the in-form Gill pulled, drove and flicked to collect four consecutive boundaries off Fazalhaq Farooqi.
Both Sudharsan and Gill dealt in boundaries to take GT to 65 for one in six overs.
Gill, in particular, was at his attacking best as he continued his onslaught and pulled SRH skipper Markram for two consecutive fours in the seventh over and then struck Mayank Markande for two more boundaries.
At the end of the 10th over, GT were 103 for one.
It was mayhem thereafter with Gill and Sudharsan going hammer and tongs to maintain a healthy run rate of over 10 till 14 overs.
Sudharsan finally departed in the 15th over, caught by T Natarajan at backward point off the bowling of Marco Jansen.
GT skipper Hardik Pandya didn't last long, giving a straightforward catch to Rahul Tripathi at point, handing Bhuvneshwar his second scalp of the day.
David Miller perished in the next over while attempting a big hit. Rahul Tewatia was the next to depart as SRH picked up four wickets in four overs.
Gill, however, went about his business and brought up his century in 56 balls with a single to long-off in the 19th over. But soon after raising his ton, Gill perished in the opening ball of the final over, caught by Samad off Bhuvneshwar.
Rashid Khan got a thick edge in the next ball and Noor Ahmad also departed during an excellent final over by Bhuvneshwar.