The Dingwall club are currently tenth in the Scottish Premier League and Adams is keen to bolster his squad when the market opens for business again in the New Year.
MacGregor says Adams had the opportunity to spend in the summer but decided not to, and he will backed again this winter as Ross County strive to finish the season strongly.
"We're going to be able to help the manager," the chairman said in the Daily Record.
"He under-spent his budget in the first six months of the season. There was money there which Derek didn't spend and it is still there so we'll look to help as much as we can.
"This transfer window in January is a difficult period because you do not get a long time to bring in players. It's short and sharp.
"The same amount of players aren't on the market so we'll need to be careful with what we do.
"But we are going to back Derek. Of course we will."
Adams had declared earlier in the week that he felt he would need to trim his squad before being able to recruit players.
He said prior to Tuesday's 0-0 draw with St Mirren: "We'll be looking to take in players in January but we'll have to offload too.
"The budget we have is not enough to carry more.
"I will have to speak to the chairman and see if we can get substantially more money. We need to move on and take in a higher calibre of player.
"We are working with the lowest budget in the top flight and if we are going to move on we need to have better funding."