Kerris, who served 14 years at Apple, joined Twitter in February with much fanfare. With Twitter's growth having stalled, Kerris was considered someone who could help re-shape Twitter's image and its message and get the company back on track.
Her arrival came after a series of shake-ups in Twitter's communications strategy, as well as at the company in general.
Twitter chief marketing officer, Leslie Berland, will now lead both PR and marketing, Twitter tells Business Insider.
Before Kerris joined, Twitter's General Counsel Vijaya Gadde had been overseeing communications, filling in for Gabriel Stricker, Twitter's previous PR boss, who left in July.
Twitter has faced a sinking stock price this year as it struggles to attract new users.
A Twitter spokesperson sent Business Insider the following statement:
"During her time leading communications at Twitter, Natalie helped us share the Twitter story with the world. We are grateful for her energy and enthusiasm and the impact she's had, even in this short time. We wish her all the best."