The official website for the TV anime adaptation of Akane Shimizu's Hataraku Saibou/Cells at Work! manga announced today that its second season is officially in the works. The news was also revealed at the anime's special stage in AnimeJapan 2019 today. More details including its broadcast schedule will be announced at a later date.

Announcement visual for the TV anime second season

????アニメ「#はたらく細胞」の第2期制作が決定！????
続報は後日発表いたします、
お楽しみに！
引き続きアニメ「はたらく細胞」をよろしくお願いします！
ゲームも是非是非あそんでくださいね???? pic.twitter.com/0QS5tm4PQY

— 『はたらく細胞』公式 (@hataraku_saibou) 2019年3月23日

The TV anime first season was aired for 13 episodes from July to September 2018, then a special

episode "Cold Syndrome" was aired on December 27 of the year. 

Kenichi Suzuki (Drifters, JoJo's Bizarre Adventure) served as director, alongside series composition

writer Yuko Kakihara (as the moon, so beautiful, Chihayafuru) and character designer Takahiko Yoshida

(Big Windup!, Yowamushi Pedal). David Production (Inu x Boku SS, JoJo's Bizarre Adventure) worked

on anime production. The whole team are expected to return for the second season.

The first season has been available on Crunchyroll. 

Source: Aniplex press release 

© Akane Shimizu/Kodansha, Aniplex, david production