It's all right now, baby it's all right now.. .

Who sang this gem?

I believe that you are referring to "All Right Now".

Performer: Rod Stewart
Composer: Paul Rodgers
Lyricist: Paul Rodgers

I am pretty sure the band was "Free". The other answer may be correct too, but they were a band.

Here's a link to some info about the group that originally recorded it:

BAD COMPANY BIOGRAPHY

Here's their lyrics:

Bad Company - All Right Now LYRICS

A Band called Free, who later some members re formed as Bad Co.

There were a number of performers to this song. I just listed one of the familiar ones.