The Bluebirds will join arch-rivals Swansea in the top flight after securing promotion from the Championship with Tuesday night's 0-0 draw against Charlton.
But Mackay insists he will have to raise the standards at the Cardiff City Stadium in the summer by bringing in top-quality players to add to his existing squad.
He told Sky Sports: "We've got a really good group here and a group that I think can challenge at the next level up. Again, to have that standard raised which absolutely is a must at Premier League level we're going to need to bring in players as well.
"How many of them? Well that's something we have to look at in the summer, but as many good players as I can basically. It's really about raising the standards.
"Again, we've done that in the first year here, raised the standards again this year and we're going to have to do it again next year.
"I think change is constant and if you don't go with change, if you don't keep pushing forward and keep trying to strive for the best you're left behind and that would certainly be us aswell and I won't let that happen while I'm here."
Cardiff's Malaysian owner Vincent Tan could spend up to £25 million on new players in the summer, but Mackay says he has yet to discuss any figures yet.
"We've not sat down with exact figures at the moment. I know the owner was thrown a question by someone a couple of months ago but myself and him will sit down.
"Me and my recruitment department have already started planning quietly as to 'what if' scenario if we did get promoted.
"We will be on going with that but it will be only players that can come in and help the group and help achieve in what we want which is to stay in the Premier League."
Victory over Burnley on Saturday would see Cardiff claim the Championship title, although two further opportunities would present themselves against Bolton and Hull should City not win at Turf Moor.