The tie-up is part of the launch campaign for Reebok's new RBK range of basket-ball footwear and clothing, which is aimed at streetwise youngsters.
The competition, which runs from October 21 to November 10, asks MTV Base viewers to create a complete track by writing lyrics inspired by music and sports and setting these to a selection of music provided by MTV.
They then send the completed CD to MTV where a panel of judges from RBK and MTV will select the top five. Visitors to www.mtv.co.uk/ rbk will be invited to vote on the best track, which will be produced in a professional studio and played on MTV Base in 2003.
Each person who votes online will be entered into a prize draw to win a trip to the US to see a New York Knicks basketball game.
To promote the link-up, MTV's sales arm Viacom Brand Solutions has created a black-and-white broadcast spot showing basketball players taking part in an outdoor game. The players perform alongside an MC and a DJ to reinforce the link between music and sport.
The move forms part of a wider strategy by Reebok of targeting young men by fusing sport with music and entertainment as its seeks to compete with rival Nike.