Kiwi arrived on Planet Namek to kill Vegeta as Freeza instructed him, but in Universe 7 he discovered as Vegeta did that Freeza and his men were wiped out by Gast Carcolh and then he realized why they've lost contact with Freeza for a while, he then teamed up with Vegeta to spy on the monster that killed his master. After the Earthlings took their lead home Gast surprised Kiwi and Vegeta demanding them to work for him, operating Freeza's spaceship so he could travel through the universe searching for a way to restore the Namekian race.
Vegeta and Kiwi later get restrained inside Freeza's ship, wile Gast fights against Coola and his henchmen, dispatching them in seconds, and Coola in 2 hits. Gast makes a deal to kill King Cold in exchange for information on how to revive his people. Vegeta and Kiwi get forced to bring Gast to King Cold's capital planet, after which Gast dismisses them, as he has no more use for them. Scared and afraid of the imminent fight between Cold and Gast, they run around and eventually find the last space pod.
Kiwi, quite stupidly; forgets Vegeta's dislike and hatred for him and suggest they both can fit inside the one pod, Vegeta promptly impales him, in his last moments, Kiwi curses Vegeta before he falls down and bleeds out from blood loss and organ failure.
Kiwi likely did not keep his guard up around Vegeta for the same reason he died in most universes, he did not know Vegeta had gotten a Zenkai boost on Earth and still thought Vegeta's level was similar to his, while in fact, Vegeta had risen to 24,000 due to the Zenkai.