Caitlyn Jenner's docuseries "I Am Cait" has been canceled after two seasons, the reality TV star announced on Tuesday, amid disappointing ratings.

The show premiered on celebrity network E! in July last year, three months after Jenner's first TV interview about transitioning from a man to a woman and giving up Bruce, the name she was known by as the 1976 Olympics decathlon champion.

"After 2 amazing seasons of @IAmCait, it's time for the next adventure," Jenner tweeted.

"Thank you E! & thank you to the best girlfriends I could ask for!"

The eight-episode first season managed an average of just 1.4 million weekly viewers, while the second season, which began in March, dipped below a million.

E! said in a statement it was "incredibly proud" of a "groundbreaking docuseries that sparked an important and unprecedented global conversation about transgender people," adding that the cancellation was a mutual decision between Jenner and the network.

The 66-year-old, an avowed Republican and perhaps the world's most famous transgender woman, became an icon of the LGBT (lesbian, gay, bisexual and transgender) movement when she announced her gender transition.