The 31-year-old midfielder, who signed for the Dingwall club in 2008, was included in a list of more than a dozen players who were told during the week that they would be leaving Victoria Park.
The Staggies fans chanted his name throughout the final Scottish Premiership fixture and after substitute Rocco Quinn scored the 77th-minute winner – striker Liam Boyce had earlier cancelled out Greg Kiltie’s opener – Brittain came on for Raffaele De Vita to take his final bow.
McIntyre, who revealed Quinn has signed for another year and De Vita has signed for two, said: “We were conscious of that fact (Brittain’s last game). He is very upset and emotional at the moment.
“It has been a difficult week for him. He has been a real stalwart at the club, at the heart of all the good moments in Ross County’s short existence in the Premiership and coming up through the leagues.
“So I don’t have anything but good things to say about Rich, he was very supportive of me.
“He also played with an injury and delayed his operation so it tells you the type of guy he is. He deserves great credit.”
County leapfrogged Kilmarnock into ninth place, a finishing position which pleased McIntyre who took over the club in September when they were bottom of the table.
The former Queen of the South boss said: “We wanted ninth and we knew the carrot was there against Kilmarnock.
“Considering where we were when we took over, sitting with no points, to finish ninth in the league has been a hell of an effort.
“I thought some of our play in the second half was excellent.
“And I thought the fans were brilliant, they were down in their numbers and dressed up – I think it was Hawaiian day – and the sun came out so everything clicked into place.”
Killie manager Gary Locke is looking for an answer from his skipper Manuel Pascali on the new one-year contract he, along with midfielder Alexei Eremenko, has been offered.
The Italian defender missed the match through injury but his former team-mate Locke needs a decision one way or the other in the next few days.
“It is up to him what he wants to do. He has been offered a deal, I don’t think he is 100 per cent happy,” said Locke.
“But he will need to make a decision in the next few days because if he is not going to be here I have to get moving and bring people in to replace him.
“Eremenko is the same and we have made a decision on most of the others, there are a few leaving. I have to put my own stamp on the team.”