The 28-year-old Henson, who recently reached the semi-finals of the BBC's Strictly Come Dancing show, came on as a replacement in the 51st minute of Saracens' 13-6 Aviva Premiership derby win over London Wasps and slotted into the unfamiliar role of outside centre.
He took less than two minutes to get the near 50,000 crowd onto their feet as he snapped up a loose ball in the Wasps 22 and raced for the line. He managed to cross near the posts, but somehow Wasps scrum half Joe Simpson got underneath him to prevent a score.
The referee went to the TMO to ask if he could award a try, but it didn't take long for him to turn down the request and leave Saracens holding onto a fragile lead.
"It was a great comeback for me and I felt pretty good out there. I slipped off a couple of tackles, but hopefully I showed enough to get a start next time," said Henson.
"It was a bit like riding a bike - it felt natural. I felt strong and felt strong in the contact area. I didn't feel like I had been out for 21 months.
"I just need a bit more time out there and a bit more time with the ball in my hands hopefully. I need to start for Saracens and, hopefully, at No12.
"I was at outside centre and I have never really played there before. I prefer playing at No12, where I can get my hands on the ball a lot more and not get bored."
Saracens' 13-6 victory moved them up into second place in the Aviva Premiership table and their next game is against Sale Sharks at the Edgeley Park on 2 January. They then face London Irish at Vicarage Road on 9 January before heading into the final two rounds of the Heineken Cup, a competition for which Henson is not yet registered.
It means the clock is ticking for the player who helped Wales secure the Grand Slam in both 2005 and 2008 if he is to force his way back into Warren Gatland's 2011 RBS 6 Nations plans. Wales kick-off their championship campaign at the Millennium Stadium against England on Friday, 4 February.
"The reason I got back into rugby was to play for my country. I would love to do it in the Six Nations, but time is running out," admitted Henson.
"The England game is my target and I would like to get at least one game under my belt before the Wales squad announcement. I just have to do everything I can in training so Saracens will hopefully give me a start.
"I need to start a game of rugby and at No12 as well because I wouldn't have thought Wales are looking at me as an outside centre."
But to get his chance at Saracens he will have to oust one of their form players of the current season, Brad Barritt and Sarries head coach Mark McCall has made it clear there is work for Henson to do.
"Brad Barritt is an outstanding No 12 and he is having a great season, so we are in no rush to move him anywhere," said McCall, who also admitted Henson will be involved against Sale next weekend.
"Gavin is finding his feet at the moment and is getting to know our systems. We are not going to rush him too much.
"Today it was sensible to bring him on at outside centre, not in a decision-making role, and just let him play. I'm not sure where he will end up for our club - I think No 12 is his best position, but he showed today he is more than capable of playing at No 13.
"It is likely Gavin will be involved over the next couple of weeks but whether he starts or is on the bench, we will have to wait and see. We then have to decide whether he becomes registered for the Heineken Cup."
Henson's last outing for Wales was on 21 March, 2009, when Ireland won the Grand Slam in Cardiff. That was his 31st appearance for his country, but he couldn't have picked a better game in which to return given the Wasps heads coach Shaun Edwards is also the Wales defence coach.
With 2009 Lions centre sensation Jamie Roberts easing his way back into rugby after a wrist operation then the two men could form a dream partnership in the Welsh midfield if they can prove their match fitness next month.
"He looked good, let's be honest. He looked pretty sharp, didn't he? Fair play to him," said Edwards.
"You always want world-class players like that, particularly from a Welsh angle."