His goal gave Celtic a 2-1 win to keep the Bhoys 10 points behind leaders Rangers at the top of the league.
The win was warmly welcomed by manager Lennon who had seen his team’s early lead wiped out. Midfielder Ki Sung-yueng gave the home side the lead in the 17th minute but defender Ryan Jack levelled for Aberdeen on the hour mark.
However, with nerves jangling, former Aberdeen defender Mulgrew drove high into the net from close range in the 72nd minute to restore the lead and confirm himself as a key part of Lennon’s side.
Mulgrew, who came through the youth ranks at Parkhead before spells at Wolves and Aberdeen, levelled in last week’s 3-3 draw at Kilmarnock — albeit it after gifting Killie a goal — and set up Joe Ledley for the equaliser in the 1-1 Europa League draw against Rennes in France on Thursday night.
The Celtic boss, who revealed Glenn Loovens and Mo Bangura will have scans today on their respective hamstring and knee injuries, acknowledged the upturn in Mulgrew’s career.
“He scored last week and set the goal up in midweek and scored again today,” Lennon said.
“He has been really consistent for us this season and I am delighted for him — I think it is the first time he has captained a winning Celtic team.
“He made a mistake last week and corrected it with the third goal.
“He has played brilliantly for the majority of the season and came up for the winner today.
“His improvement since he came back here has been huge.’’
Immediately after Ki’s opener, Loovens, having picked up an injury, was replaced by the man he had recently replaced in the side, Daniel Majstorovic.
Lennon bemoaned yet more injury woe, a recurring theme of the Irishman’s season.
“We lost Glenn through a hamstring injury so we have to wait and see the extent of that tomorrow,” said Lennon.
“It could be a reoccurrence of the injury he had, we are not sure but he was feeling it and he will have a scan.
“We lost Mo Bangura yesterday, he has a swollen knee and he is going for a scan tomorrow as well so we don’t know how long, if any length of time at all, he will be out for.
“We are up against it but I am really pleased with the players, especially the ones who played against Rennes on Thursday.”
Aberdeen ended up with 10 men after Jack was sent off with 10 minutes remaining after picking up the second of his two yellow cards.
The Dons defender, already booked for over-celebrating at his goal, was shown a second yellow by referee Stevie O’Reilly for a foul on Gary Hooper.
Visiting manager Craig Brown was “aggrieved” with the decision, saying: “I don’t want to change the laws because we had a man sent off but to be cautioned for over-celebrating was harsh.
“A word in his ear might have done it.
“The fourth official said he was warned not to go off but he wasn’t in the crowd so I think it was a bit harsh.
“The second one – there were other fouls in the game equally bad which didn’t result in a caution so I feel a little aggrieved but I never criticise the officials.
“I am not blaming the ordering-off for losing the game but it made it a mountain to climb, man short, away from home against a team fighting to stay in SPL contention.”
Elsewhere Steven Naismith and Nikica Jelavic were both on target as Rangers claimed victory over Hearts to strengthen their grasp on top spot in the Clydesdale Bank Premier League.
Naismith grabbed his ninth goal of the season, before Jelavic – rated doubtful ahead of the game – doubled the advantage just a few minutes after coming off the bench.
The win allowed Rangers to stretch their lead over second-placed Motherwell to nine points.