The talk show host was looking like a princess Wednesday -- quite literally -- as she walked out of a NYC TV studio wearing a giant tiara and a hot pink outfit, in which she showed off some leg. She was all smiles as she got into her waiting vehicle, and for good reason too ... the surrounding paps belted out a heartfelt 'HB' a day before she hits the big 5-5.

Yes, Wendy is turning 55 Thursday ... and the crush of photogs let her know how much she meant to them with a song (for a soundbite, of course). She seemed to appreciate the gesture though, thanking everyone who sang as she climbed into the car.

Wendy's got every reason to celebrate -- her family drama seems to be simmering down after her son, Kevin Jr., was cut loose by prosecutors after he got into a scuffle with his dad.

Of course, she's still in the middle of an up-and-down divorce with her estranged husband/biz partner, Kevin Hunter, but even in the love department ... she's doing alright.

Wendy's been hanging with a young buck, who seems to be keeping her busy from coast-to-coast. He's already said he's not using her .. just enjoying her company, and vice versa.

If anything ... her smile here is a most welcome 180 flip from what we saw her doing about a month ago, when she was shedding tears on camera over her family.