The substitute's emphatic 79th-minute finish from Lewis Stevenson's cross earned Hibs a 1-0 win over Dundee and seventh place in the Clydesdale Bank Premier League.
Hibs dominated the Easter Road clash and ensured they return to Hampden to face Celtic in the William Hill Scottish Cup final on May 26 unbeaten since their victory over Falkirk in the last four.
Fenlon also avoided any injuries after naming a strong team which included top goalscorer Leigh Griffiths in the starting line-up.
The Irishman said: "We were looking for a performance and we got one of them. I was pleased to pick up three points, no injuries and a decent performance.
"We probably couldn't ask for any more. We spoke about that when we won the semi-final, to give ourselves momentum and confidence going into the final.
"The players have responded very well because it could have been easy to limp our way through to the final but we have had some decent performances along the way."
Fenlon rested midfielder Kevin Thomson and is hoping for a full squad for Hampden with James McPake and Tim Clancy set to train on Tuesday following injury. And he was relieved not to have had the distraction of a rearranged game after the pitch passed an inspection following heavy rain in Edinburgh.
Fenlon said: "We didn't want it dragging out until Tuesday or Wednesday, that's for certain. We would have had to just put all the kids out at that stage.
"But thankfully the pitch played really well, the rain helped rather than hindered."