Custom Robo Arena, known in Japan as Gekitō! Custom Robo, is a science fiction action role playing game for the Nintendo DS. It is the fifth title in the Custom Robo series. The name was announced on May 9, 2006 at the E3 convention, and released in Japan on October 19, 2006, then later in the United States on March 19, 2007. Later, on May 25, 2007, it became the first Custom Robo title released in Europe, and on September 20, 2007, it also became the first title of the series released in Australia.

In the game, the player participates in Custom Robo tournaments and tries to earn money to buy parts to use to improve their robo. The game is the first in the series that features two-player mode with the Nintendo Wi-Fi Connection including voice chat, Multi-Card play, and DS Download Play. Custom Robo Arena also uses a "Rivals" list.