Ian Holloway’s side endured a difficult first half at the Nigel Eady County Ground on Saturday, but produced an emphatic response after the break.
Colchester took the lead after just 13 minutes when Moses Sesay released Kylian Kouassi, who powered the ball beyond Connor Ripley and into the roof of the net.
Swindon had started brightly but struggled after falling behind, with the visitors increasingly taking control of the contest.
Former Town midfielder Jack Payne fired over as Colchester looked to build on their advantage, while the hosts struggled to rediscover their early intensity.
Holloway made three changes at half-time, introducing Kaelan Majekodunmi, Ben Middlemas and Louis Millard in place of Billy Kirkman, Antwoine Hackford and Ollie Clarke.
The substitutions had an immediate impact and Town were handed a route back into the match within four minutes of the restart.
Anthony Munda was brought down inside the penalty area and referee Sunny Singh Gill pointed to the spot.
Drinan saw his penalty saved by goalkeeper Thimothee Lo-Tutala, but reacted quickest to smash home the rebound and make it 1-1.
The equaliser shifted the momentum firmly in Swindon’s favour. Millard was later forced off through injury, with Wigan Athletic loanee Joseph Hungbo introduced in his place.
Hungbo caused Colchester problems with his pace and direct running on the right, curling an effort narrowly wide before later forcing Lo-Tutala into another save.
Swindon24 sports reporter Ian Howard said:
“That was the ultimate game of two halves. Town went behind to a goal early on and struggled to break down Colchester. The second half brought on Hungbo who gave width and pace leading to Drinan adding to his penalty to achieve a hat trick. The crowd went home happy and Town move into second place in the league.”
Town completed the turnaround in the 77th minute after Hungbo collected a long pass from Dan Butler and picked out Mitch Clark inside the penalty area.
Colchester initially challenged Clark, but the loose ball fell to Drinan and the striker fired emphatically beyond Lo-Tutala.
Just two minutes later, Drinan completed his hat-trick. Hungbo released Jack Thomson down the right before Thomson found Drinan inside the area, where the Irishman calmly slipped the ball through the advancing goalkeeper’s legs.
Drinan recently signed a new contract which keeps him at Swindon until 2030, having finished as League Two’s leading scorer last season.
After the match, Holloway praised the striker and the club’s work to retain him, describing Drinan as “above the level” and backing him to score heavily again this season.
The victory means Swindon have won their opening three home league matches of the campaign, having also beaten Cheltenham Town and Port Vale.
Town had not achieved that feat since their League Two promotion-winning season in 2006/07.
A crowd of 8,253 watched the comeback, which moved Swindon onto 10 points from their opening five league fixtures.
Bristol Rovers remain top on 12 points following their 1-0 victory over Rotherham United, while draws involving Barnet, Walsall and Crewe allowed Town to climb above the chasing pack.
Swindon’s latest victory also continued an immediate response to their 3-0 defeat at Oldham, with Holloway’s side recording successive 3-1 home wins over Port Vale and Colchester.
