Bluebirds substitute Craig Noone scored a second-half free-kick to cancel out Chris Eagles' 19th-minute opener and Mackay was understandably overwhelmed at the final whistle.
"To win promotion against Charlton was fantastic, to win the title in front of 2,000 of our fans at Burnley was great," he said.
"But to lift the trophy and have the medals here at our stadium in front of 27,000 people is something that will live with me forever.
"Our families make sacrifices for us as footballers, and it is nice on days like this for them to be involved as well.
"I am proud of everyone at the club. It means a lot to the club and the city and it gives everyone a great sense of pride.
"We have been pulling in the right direction for 99 per cent of the season and when you do that, titles are won. It's a day I will never forget."
The Scotsman was also pleased with the way his side fought back from a goal down in a match that was a dead rubber for them but which remained relevant to the play-off picture.
"People asked what the point of this game was for us. The point is the integrity of the league, which we respect immensely," added Mackay.
"Bolton needed to win to try and get in the play-offs.
"We had 27,000 people pay to be here and they were here for a party, but we wanted to give them a good game and I knew the side I put out would not let a pre-season type of game happen.
"It is about proving you are champions in front of your own crowd and at times today I thought we were exceptional, so I am very proud to put in a performance like that with nothing much to play for."