Brad Pitt Joined by Girlfriend Ines De Ramon For 60th Birthday Celebration

Brad Pitt is looking and feeling youthful at 60 ... ringing his milestone birthday with his much younger girlfriend, Ines de Ramon, by his side.

Pals joined the Hollywood sex symbol -- yes, even at 60 -- and 33-year-old jewelry designer as they headed out to L.A. hot spot, Mother Wolf, Tuesday evening -- a day after Brad's actual birthday.

Brad ensured he'd have all eyes on him by showing off some loud style in a black and gold-foiled shirt ... while Ines wore a white mini dress.

The couple's been dating for a year now ... and it's his first proper relationship since his bitter divorce from Angelina Jolie.

He's reportedly introducing her to folks as his GF these days ... so, clearly things are going well for the duo.

Earlier this week, huge 60th bday balloons were seen being dropped off at the Bulgari Hotel where he was staying in Paris.