Janet Jackson was ready to let her hair down after performing two sold-out shows of her “Together Again” tour at Madison Square Garden this week.

The pop icon called up designer pal Christian Siriano for a night out on the town, a source told Page Six.

“She wanted to go dancing, and asked Christian where to go,” the source said.

Siriano then hit up his DJ pal, Ty Sunderland, in the middle of the night and had him come to Nolita’s latest hot spot, the Mulberry, at around 1:30a.m., to spin for Jackson and her dancers.

We’re told patrons left at the 2a.m. closing time, but Jackson and Siriano stayed with their crew, dancing until after 5a.m.

“Christian took over the bar, bartending, and made shots for everyone,” the source said.

Siriano was spotted at Jackson’s Monday night MSG show, where he danced with pals Alicia Silverstone, stylist Leah Snow and his designer boyfriend Kyle Smith.

Jackson and her dancers wear Siriano’s design during the “club portion” of her show and we hear he’s working on new looks for the “Control” singer.

This isn’t the first time Jackson enlisted the designer to take her on an escapade around New York.

The duo had their first in-person meeting at Siriano’s New York Fashion Week show last September.

Jackson also attended a private dinner the designer hosted, and then later partied at the Paradise Club at the Times Square Edition Hotel where a DJ spun her tunes all night.