She began her cinematic career working as a set designer, script doctor, and art director on such films as Elia Suleiman's The Time That Remains (2009), Ziad Doueiri's The Attack (2012); followed by Adi Adouan's Arabani (2014) and Rafael Najari's Over the Hilltop (2014).

In their reasoning, the judges wrote: "It is a creation that is entirely love of humankind, fluent and funny, captivating and kindhearted, a contemporary human mosaic, both local and universal.

[7] Then Israeli Minister of Culture Limor Livnat established regulations that require any project receiving public funds to be presented as strictly an Israeli feature, not as a Palestinian-Israeli or Palestinian film, causing difficulties for filmmakers like Haj who want to highlight their Palestinian and/or dual identities.

Ultimately, the IFF backed the project after Haj and her producer agreed to the terms to release the movie as an Israeli feature.

In 2022, Mediterranean Fever, which she wrote and directed, premiered at the 2022 Cannes Film Festival within the Un certain regard section, and won the Prize for Best Screenplay.