"I don't have any negative feelings towards @LaurenConrad," 29-year-old Montag tweeted on Wednesday afternoon.
"I wish her nothing but the best!" the tweet continued.
The duo had an up-and-down friendship throughout the six seasons of The Hills, with Montag's now-husband Spencer Pratt primarily at the centre of the duo's drama.
Conrad admitted during the hour-long special that although the show "doesn't always bring back the best of memories," she doesn't regret her reality TV past.
"While it was hard at times, it brought me to a place where I'm really happy and I get to do what I love and I feel really lucky. So, going back I would still do it again."