The 28-year-old started his first match since returning to his first senior club earlier in the month in a deal that will see him play for free through to the end of the campaign.
The performance of the former Rangers midfielder, whose injury-ravaged spell at Middlesbrough was cut short in January, was not enough to prevent Hibs from slipping to a 2-1 defeat to Inverness Caley Thistle that leaves their top-six aspirations hanging by a thread.
However, with a Scottish Cup semi-final against First Division Falkirk to follow on Saturday week, Fenlon is convinced Thomson, who started his first league game in six months against Caley Thistle, can play a key role in what could prove a historic few weeks for his boyhood idols.
He said: “Kevin Thomson came in and did really well for us, he played well. He’s very assured on the ball, he keeps it well and passes well, and is always available to receive passes.
“He’ll be a big player for us between now and the end of the season. I thought he was excellent and that will help him as well, to get that 90 minutes under his belt.
“He’s trained really well and we just felt he was close enough to get him into the team.
“He gave us a different dimension, he was very calm and assured on the ball.”