BabyMonster's Ahyeon Rejoins Group After Missing Debut Due To Health Issues

K-pop group BabyMonster is back to being a septet -- 'cause Ahyeon has rejoined her fellow members after missing their big debut to focus on her health.

YG Entertainment just announced the big news Wednesday ... saying Ahyeon has "fully recovered" from her personal issues and is currently working on the group's upcoming projects.

He said in a video message ... "From the mini-album onwards, you can look forward to BabyMonster's activities as a perfect seven-member group" ... adding any previous work will be re-recorded to include Ahyeon's vocals.

Yang also said the group's EP will drop April 1 ... and the plan is to release their first full-length project later this year.

As we previously reported, the 16-year-old singer left the ensemble shortly before its first single, "Batter Up," came out in November ... with only Ruka, Pharita, Asa, Rami, Rora and Chiquita taking part in the audio recording and music video.

Despite Ahyeon's absence, the visuals racked up more than 200 million views online.

It's more great news for YG -- in December, it was reported BLACKPINK's Jennie, Jisoo, Lisa and Rosé agreed to stay with the label for all group-related activities while going elsewhere for solo work.

Fans are also excited ... as Ahyeon was considered to be one of the biggest rising stars in the industry, even drawing comparisons to Jennie due to her wide-ranging skills on the mic.