Both synonymous with London shopping, but which actually came first?
Carnaby Street derives its name from Karnaby House, located to its east and originally erected in 1683. The street is thought to have been laid out in 1685 or 1686 – first appearing in the ratebooks in 1687.
Although Oxford Street follows the route of an original Roman road (linking Hampshire with Colchester), it did not become known as Oxford Street until around 1729 (until then it was variously known as Tyburn Road, Uxbridge Road, Worcester Road and Oxford Road).
Once again, thanks to Wikipedia!