"Brand New Key" is a pop song written and sung by folk music singer Melanie. Initially a track of Melanie's album Gather Me, produced by Melanie's husband, Peter Schekeryk, it was known also as "The Rollerskate Song" due to its chorus. It was her greatest success, scoring No. 1 on the Billboard Hot 100 singles chart during December 1971 and January 1972. Billboard ranked it as the No. 9 song of 1972. It also scored No. 1 in Canada and Australia and No. 4 on the UK Singles Chart. The song was featured in the 1997 movie Boogie Nights as well as the 2010 movie Jackass 3D and an episode of Helix.

Who sang i got a brand new pair of rollerskates? Let's have some stream of consciousness first.
To answer the question, consider the following: "Brand New Key" is a pop song written and sung by folk music singer Melanie. So, the answer is folk music singer Melanie.