Pitch Marketing Group, which had held the account with the North American sports league for more than a decade without repitch, was one of several agencies invited to bid for the business in June.
Maik Matischak, NBA EMEA senior comms director, told PRWeek the NBA felt obliged "to test the market and see what other agencies were out there".
He said: "Despite this, we're very happy to be continuing working with Pitch."
Pitch’s remit includes consumer and sports PR, media relations, and press office duties throughout the UK. This includes helping to grow the NBA's fanbase outside of the US, and promoting the league's annual game in London.
Pitch also manages a six-strong network of agencies throughout Europe and the Middle East. The agencies are tasked with promoting the NBA in their individual regions.
A spokesman for Pitch said: "We rely on these agencies for 'the final mile' and their local expertise. They give us access to media and influencers, and they create bespoke content for use in their regions."
Pitch, which specialises in sports and entertainment marketing, has clients including the UK's Premier League, which it started working on in September, BT and its growing enterprise BT Sport, and the Football Association.
US sports have worked hard to increase their profile overseas in recent years, particularly in London and the UK - Major League Baseball hired UK agency W Communications for a European campaign earlier this year, while the NFL team Jacksonville Jaguars, one of several to have played games in the UK capital in recent years, recently took on FleishmanHillard to position it as London's "home team".