The black and white snap was posted onto DeLeon's Instagram account to his 137K followers with the message: "hat game strong."
Swift wrapped her arms around 26-year-old Williams as Zedd made his best funny face as they all donned cone-shaped paper birthday caps.
Also in attendance at the star-studded gathering was Selena Gomez as Swift posted a photo of the two gal pals embracing at the bash.
Perfectly at ease in each other's company, the two pop singers gave each other a knowing glance as they sang around a birthday with lit candles.
The longtime friends also posed for another group shot together along with gal pals Jaime King, Hailee Steinfeld and birthday girl Cabello.
This time last year it was reported that Swift had disapproved of Gomez's reconciliation with bad bot Justin Bieber.
Sources told Us Weekly at the time that Swift had begun distancing herself following Gomez's brief relationship with Ed Sheeran in 2013.
Sheeran is also a close friend of Swift's and she felt he was used by Gomez to make Bieber jealous.
And, the magazine revealed, the news that Gomez and Bieber had spent a March 2014 weekend together was the final straw for Swift - who was "disgusted" by her former pal's decision.
Though Gomez and Swift appeared to grow apart in the public eye, the Shake It Off hitmaker maintains that there never was a feud, instead saying she and Gomez used to laugh about it, together.
Speaking to Rolling Stone magazine at the end of 2014, Swift said: "People think they have my relationships all mapped out. There were all these blogs, like, "Are they feuding? Are they fighting?"'
"Meanwhile Selena and I would be on the phone that night, laughing about it. We let them have that one."
Birthday goals
It was only a matter of time until this happened...
Forget the haters somebody loves yaaaaah
Meanwhile in Germany
The Countdown is on!
I think she accidentally brought her Meerkat.
Tom Hanks collaborating with Carley Rae Jepsen!
* Cam Mansel is the host of iHeartRadio's Ultimate Access.
- nzherald.co.nz / Daily Mail
