After watching Lady in the Water (2006), József Gallai decided to deal with filmmaking and started writing screenplays and short stories. Between 2009 and 2012 he was mainly involved in amateur films in various genres.

In 2014, he wrote and co-directed Hungary's first feature length found footage horror Bodom (2014). In this year the movie opened the Bram Stoker International Film Festival in Whitby, UK as well as collected numerous nominations on film festivals including 30 Dies Festival in Andorra, Golden Rake Award for Indie Horror and New York Scary Film Awards in the US and Amazon Horror Awards in Brazil.

In 2015 Bodom was in the final competition at the Full Moon Horror & Fantasy Film Festival in Romania, competing with award winning films such as Welp (2014), Horsehead (2014) and Réalité (2014).

In the beginning of 2016 his next horror movie Moth (2016) was completed and finished 4th Best Feature Film at the International Horror Hotel in Cleveland, Ohio. The movie has been called a "thought-provoking and chilling film" by Found Footage Fiction and a "front running for a new horror niche" by Horror Habit. According to Horror Asylum, Moth is "an unusual experience with some moment reminding the author of David Lynch's Inland Empire (2006)".

In the end of 2016 Gallai finished his fourth found footage feature A Guidebook to Killing Your Ex (2016), being described as an "enjoyably sinister movie with a delightfully unhinged central performance" by UK Film Review and collecting further positive reviews from Found Footage Critic, Top Found Footage Films and Warped Perspective as well as three nominations (including Best Original Screenplay of a Feature Film) on the International Filmmaker Festival World Cinema in Nice in 2017.

In 2018 he completed his next short film Echoes (2018), which will be part of a horror anthology titled Blood Tales. He also directed two internationally acknowledged films in 2019 (Spirits in the Dark, The Whispering Man) that are set to be released worldwide in 2020 by Wild Eye Releasing.

Presently, Gallai is working on his next paranormal thriller The Poltergeist Diaries featuring Oscar nominated Eric Roberts.