Imran Qayyum took a wicket on his NatWest T20 Blast debut but an under-par Spitfires total meant Gloucestershire sealed a six-wicket win in the final over at Cheltenham.
Joe Denly (39) top-scored in a opening stand of 45 off 31 balls with Daniel Bell-Drummond (16) before the hosts struck regularly to stunt the Spitfires scoring at The College Ground.
Sam Billings hit 36 off 25 balls but could not share a substantial partnership as Darren Stevens (19) and Adam Milne (17*) were the only others to reach double figures.
In reply, James Tredwell struck to bowl Michael Klinger in the sixth over to leave Kent in the hunt before his opening partner Phil Mustard (42) and Ian Cockbain (31) struck 41 in 4 overs to get the hosts ahead of the run rate.
Mustard became Qayyum’s first victim in professional T20 cricket before Australian batsman Cameron Bancroft (34*) and Benny Howell (22) steadied the ship.
New Zealand paceman Adam Milne removed Cockbain and Howell before Jack Taylor hit a boundary off his first ball to seal victory.
After the match, 24-year-old Qayyum said: “I suppose it’s a case of mixed feelings for me. It was great to get my debut after being on the staff for four years, but I am disappointed that we lost.
“I suppose we were always playing second fiddle to Gloucestershire, but with four or five overs left, we were still in with a chance.
“Fair play to Gloucestershire, they got it right on the day and all credit to them. We just need to bounce back straight away if we can.”
The two sides meet again on Tuesday (18 July) at The Spitfire Ground at 7pm.