Steven Caulker's second-half header lifted the gloom at the Cardiff City Stadium on Sunday against a backdrop of uncertainty over Mackay's future following owner Vincent Tan's decision to replace head of recruitment Ian Moody with 23-year-old Kazakh Alisher Apsalyamov.
Apsalyamov has since been forced to step aside over issues with a visa as the club's fans continue to voice their disapproval of Tan's ownership.
However, victory in the first top-flight Wales derby moved Cardiff above their fierce rivals, who finished with 10 men after goalkeeper Michel Vorm was sent off for a foul on Fraizer Campbell late on.
And Mackay was quick to recognise the importance of the result.
"It's a great day, and in terms of the background noise over the last few weeks it certainly helps," he told Sky Sports.
"It's put smiles on people's faces here and I've never seen an atmosphere like it. And it was not only the win, but also the performance. I thought we were very dominant.
"It's a tough, uncompromising league but it's the only place to be. We've got good people here and we enjoy playing here in this division."
Match-winner Caulker spent a year on loan at Swansea during the 2011-12 season before joining Cardiff from Tottenham in July.
The England international was delighted to have made the difference for his side, but stressed that he still held respect for Swansea after refusing to celebrate his goal.
"It was really intense, especially the last 10 minutes when we were sort of clinging on, but the boys have done really well and stuck together," he said.
"It was a different experience playing against them. I enjoyed my time there, but I'm a Bluebird.
"I was thankful to get the win for us, and even more pleased to get the goal. I always respect the teams I've played for. They took me in a couple of years ago, so there's no hard feelings."
