Bentley saw former Miller Kevin Ellison score a dramatic 90th minute winner to give his side their first victory in seven games, much to his delight.
He said: "It was an unbelievable finish to the game with Kevin Ellison doing what so many players do against their former clubs and scoring a great goal.
"It meant a lot to us because we haven't won for a few games and I wanted to make sure we moved further away from the bottom clubs because it was all getting a bit tight down there.
"On Monday we lost to Wycombe in what was the worst display I have seen as manager and I wanted a response. I got that and I'm delighted for the lads because they are a good, honest bunch who always give their all and this is a reward for those efforts."
Ellison's goal came after the visitors had been reduced to 10 men when skipper Johnny Mullins was sent off with 19 minutes remaining for fouling Wright as he looked set to run on goal.
It proved a big decision as Rotherham had come from behind when Alex Revell deflected a Lionel Ainsworth shot past Barry Roche just after the hour.
Morecambe had started the second half in style when left back Robbie Threlfall scored his first goal for the club with a superb free kick.