Nixon will oppose current New York Governor Andrew Cuomo in the upcoming Democratic Primary.
On Wednesday, it appeared Parker was still not 100 percent on board with Nixon's campaign.
"Cynthia has been my friend and colleague since we were little girls", Parker said, through a spokesperson.
Calling Nixon "my sister on and off screen", Parker, who played Carrie Bradshaw, told her former castmate that "you have my love, support and vote".
The socially shared words of encouragement follow speculation that Parker wouldn't be pairing her signature stilettos with a "Nixon for Guv" T-shirt anytime soon.
Parker, Nixon, Cattrall, and Davis starred as four single women and best friends in New York City on the HBO hit "Sex and the City" from 1998 to 2004 and its two feature film sequels.
"I support and respect any former colleague's right to make their own career choices", she tweeted.
So the far-more-enthusiastic Thursday Instagram puts her in the same camp as Davis, who immediately after Nixon announced her run for the Empire State's Democratic nomination, publicly backed her former co-star. "I'm so proud of her and I know she will work tirelessly to create change for all who need representation".
"New York is where I was raised and where I'm raising my kids", she said in an ad announcing her candidacy.
Kim Cattrall also tweeted her support. If Nixon's run turns out not to be the one thing they can all agree on, at least we know that avoiding more drama surrounding the show seems to be top at all of their lists of priorities.