Taylor Swift helped Dakota Johnson celebrate her 37th birthday at the star-studded “Saturday Night Live” after-party this weekend with A-list friends, greasy food and a stealthy entrance.

The “Love Story” singer secretly snuck into the fancy fête at L’Avenue at Saks after crashing Johnson’s “SNL” monologue earlier in the evening, a source exclusively told Page Six.

“Taylor came, but didn’t use the L’Avenue entrance,” the insider shared, adding that the singer was only there for “about an hour.”

We’re told the pop star, who was joined by pals Cara Delevingne and Ashley Avignone, was spotted noshing on French fries while situated at a table right next to Johnson’s setup.

“Everyone was crowding around for Dakota’s birthday,” the source added. “The vibes were great.”

A second source told us that the “SNL” cast helped mark the “Fifty Shades of Grey” actress’s D.O.B. with oversized silver balloons spelling out her name.

Spotted at the celebration was the band Turnstile, who performed as the musical guest during Saturday night’s episode, as well as “SNL” cast member Michael Che.

Also bringing starpower to the evening was Nathan Fielder, Stephen Spielberg, Gabby Windey, Robby Hoffman, John Wilson, Shane Gillis, Kelli Finglass, Shai Fruchter, Dom Dolla and more

We hear Dom Dolla was spotted chatting and mingling with guests following his show for 40,000 fans in Queens.

Earlier in the evening, Johnson returned to Studio 8H for her third “SNL” hosting stint, with Swift making a surprise appearance during the actress’s monologue.

During the opener, Johnson lovingly referred to Swift as her “therapist,” while the singer playfully jabbed back, “I’m not your therapist, actually. You just show up at my house once a week with an empty bottle of wine and ask me if I want some.”

Swift — wearing a plaid off-the-shoulder Simkhai dress — also presented Johnson with a birthday cake at the end of the show.

Page Six also exclusively reported that Johnson continued her birthday celebrations on Sunday evening with a festive dinner at Via Carota in the West Village.

The “Verity” star arrived at the Italian hotspot wearing a velvet and lace dress layered under a fur-trimmed coat.

Johnson was joined by Jennifer Lawrence and her husband, Cooke Maroney. However, we’re told Swift wasn’t spotted at the dinner.

The “All Too Well” artist, 36, and Johnson have been close friends for more than a decade.

Johnson and Swift have been spotted out and about in Manhattan on several girls’ nights, including sightings at Via Carota, Wavery Inn, and other dining destinations.

The actress even starred in Swift’s latest music video for her song, “Patient Zero.” The project, also starring Colin Farrell, premiered during the 2026 MTV Video Music Awards last on Sept. 27.