Justin Bieber Rocks New Hairstyle Proudly on Dinner Date with Hailey

Justin Bieber's fortunate there were no birds around as he headed in for his dinner date with Hailey, or they might have tried to set up shop on his new 'do -- a pulled-back take on locks.

The Biebs and his wife hit up Craig's restaurant in WeHo Monday night, arriving with very contrasting styles -- Hailey dressed to the nines, while JB had a more chill teen look ... at least it matched his bird's nest-like hair.

Speaking of that new coif, Justin partially covered -- or wrapped -- his locks with a black bandana, and umm ... pulled them back into pigtails. Ya can't say he's half-stepping into the new look.

Justin rounded out his ensemble with sneakers, jeans and a baggy red sweatshirt ... and seemed to be in his own world on his phone.