The 18-year-old was unexpectedly thrust into the limelight after striking what many believe will be the most important goal he will ever score as Celtic put the Spanish giants to the sword in an incredible evening at Parkhead.
It earned Neil Lennon's side a hugely surprising 2-1 Champions League victory that shocked the footballing world and has now gone down as one of the most famous results in the club's 125-year history.
With the dust now just beginning to settle, Watt has had a chance to evaluate the consequences of what many described as a life-changing moment – but it has been anything but according to the Hoops hitman.
"It was great to score a goal against Barcelona and even better that it turned out to be the winning goal," said Watt, who is hoping to shake off the effects of an ankle knock as quickly as possible to maintain his run in the side.
"It was the biggest game I've ever been involved in and to come off the bench and find the back of the net was such a great feeling.
"It was actually my first appearance in the Champions League because I didn't feature in the previous matches at home to Benfica or the two away games against Spartak Moscow and, indeed, at the Nou Camp against Barcelona.
"So to score, and to help the club beat such an unbelievable team such as Barcelona, was a great feeling.
"The next day, though, I just met up with my pals and it was just like any normal day off. I'm not the type to let things go to my head; I'll never get carried away or become arrogant because I'm not that sort of person.
"Also, I know what I need to improve on and there are aspects of my game that I need to work on, so it's not as though I think I'm the finished article.
"My family wouldn't allow it for a start and neither would the gaffer, Neil Lennon. And the same goes for my team-mates. So my feet are very much on the ground."
Watt, however, admits he is extremely proud to have played his part in a night which is likely to live long in the memory of the Celtic supporters.
"The atmosphere when I scored was unbelievable," said Watt. "The place just erupted but it was like that all night.
"Before the game, the noise levels were frightening and the supporters were great from start to finish. They really look forward to the European nights and it was great that we managed to get the victory for them.
"People have been saying it is one of the best nights ever at Celtic Park and it is just fantastic that we managed to beat Barcelona, especially after coming so close to earning a draw over there when we lost a goal in the 94th minute to lose the game 2-1.
"Barcelona are obviously a wonderful team and to have any chance of beating them you need everyone to be at the top of their game, but I think we got that last week. Fraser Forster was the key man again in goal, but everyone raised their game."
Celtic were then brought back down to earth with a bang at the weekend when they were held to a 1-1 draw at home to St Johnstone.
It required the introduction of Watt at the interval for them to conjure up the opening goal when the young striker netted with what was practically his first touch of the ball, taking his tally to three goals in his last three matches.
But the striker, who was forced to withdraw from the Scotland Under-21 squad as a result of an ankle injury he sustained during the match, added: "It was disappointing not to win the match.
"That's twice in our last two league games we've lost leads and ended up drawing the match. We need to start trying to win more league matches to get back to the top of the table.
"It's great doing well in the Champions League and it would be amazing if we were to actually qualify for the knockout stage of the competition, but we also have to focus on the league and the domestic cup competitions."
Having scored one and created a second in the 2-2 draw away to Dundee United in the previous match, Watt might have been entitled to believe he had just about done enough to merit a starting slot for the visit of Barca.
"I never played well enough against Dundee United," said Watt. "I might have scored and helped set up the second goal, but my overall performance wasn't as good as I am capable of. I knew that myself after the game.
"But it was really nice to score another goal against St Johnstone and, hopefully, I can continue to find the back of the net and help the club be successful."