Early on in her career, Allen made appearances in various television shows such as the sitcom
Dr. Ken, the drama series
SEAL Team and the sitcom
Teachers. She was then cast as a younger version of
Mary Elizabeth Winsteads character in the action film
Kate.Her first lead role was as Beverly in the comedy film
Mixtape. During filming Allen became close with co-star
Julie Bowen and taught her
Tik-Tok dances. She got to keep the mixtape after filming was complete{{Cite web |title= Fun Facts from Netflix's MIXTAPE: Cast Interview with Julie Bowen and Gemma Brooke Allen == Personal life ==