The Rs became the first promoted club for more than 10 years to beat the Blues.
"The lads are really confident as a dressing room, but it is not often a promoted side can play one of the top four and get a result," Mackie said.
"When they came to our place it was a great atmosphere for everyone and I think the lads did really well.
"On days like that I think you need a bit of luck against the top teams.
"It was nice to get [our first home win] and to do it against Chelsea is even better for the fans so we can kick on now.
"I think our home form has got to be top draw for us to do well this season and I am sure we can kick on now."