The singer was performing her track 'Judas' at a gig in Auckland as part of her 'Born This Way Ball' tour when the incident occurred.
One of her backing dancers - reportedly named Mark - accidentally hit her on the head with a heavy pole during the song.
Lady GaGa's make-up artist Tara Savelo later confirmed that she had suffered a concussion, but that she has recovered well, according to GaGa Media.
After the incident, the star told the audience: "I want to apologise, I did hit my head and I think I may have a concussion but don't you worry I will finish this show."
She then proceeded to complete the gig, which contained 16 further tracks.
The phrases "#GetWellSoonGaga" and "#PrayForGaga" have become trending topics on Twitter since last night's gig.
Lady GaGa is said to have responded to Madonna's recent mash-ups of her material during a separate Auckland gig this week.