The coach at the time didn't like the look of the striker, so he cut the trial short after just one day.
He would later sign for Celtic and go on to score one of the most memorable goals in the club's recent history, the winner against Barcelona in a famous Champions League victory.
He said about his trial with Rangers: "I went for one day but it didn’t work out. The head of youth liked me but the coach didn’t so it didn’t feel right.
"I don’t think it was because I was a Celtic supporter but I didn’t get the impression it was going to be for me.
"I was as Airdrie at the time and they’d let players go on trial to get moves. I also went to Liverpool for a few days."
Watt has recently been linked with a move to CSKA Sofia after leaving St Johnstone.