Punjab Kings and Royal Challengers Bengaluru, who are both on 17 points after 12 matches, also qualified for the knockout stages.
For GT, opener Sai Sudharsan (108 not out off 61 balls) and skipper Shubman Gill (93 not out off 53 deliveries) chased down the 200-run target with six balls to spare.
Earlier, invited to bat, opener KL Rahul displayed great intent on a slow and grippy wicket to score his fifth IPL century as Delhi Capitals scored 199 for 3.
Rahul scored a 65-ball unbeaten 112.
Brief scores: Delhi Capitals: 199 for 3 in 20 overs (KL Rahul 112 not out, Abhishek Porel 30; Sai Kishore 1/47, Prasidh Krishna 1/40).
Gujarat Titans 205 for no loss in 19 overs (Sai Sudharsan 108 not out, Shubman Gill 93 not out). PTI APA AM APA AM AM