The 21-year-old scored the winner for Man United as they beat Liverpool at Old Trafford to secure Champions League qualification.
United have had a remarkable turnaround, winning ten, drawing two, and losing two games in the Premier League since Carrick, 44, took over.
Speaking to Sky Sports after the game, Mainoo, who has been reintroduced to the starting line-up under Carrick, was full of praise for his manager.
"Happy to turn it (the season) around, it's a credit to all our players and the manager as well. We still need to finish the season strong, this is not enough for us,” he said.
On himself playing a role today after coming back into the squad: "It was difficult of course, anytime you're not playing football. I just tried to look forward as much as possible and to keep my head down."
On Carrick: "He's played a huge part in it, all the confidence he gives all the players. You want to follow him and fight for him and die for him on the pitch."
On the first-half performance: "Happy to be around the goals in this game, such a special game and fixture."
On scoring his first senior goal at the stadium: "I saw a couple of my family members, it's a blessing to play and a blessing to score. I used to sit in that corner, I'm just so blessed to be in this position. I used to dream of times like these. I'm glad to be here with the club."