Mbithi directs films, music videos, and commercials. His first feature film Kati Kati, produced by German director Tom Tykwer and One Fine Day Films, has been screened at 40 festivals globally and went on to win several international awards, including the International Federation of Film Critics (FIPRESCI) award in the Discovery Programme at the 2016 Toronto International Film Festival (TIFF). FIPRESCI described Mbithi's work as 'an exciting and unique new voice in cinema'. Kati Kati was announced by the Kenyan Film Commission as the official Kenyan submission for the Best Foreign Film Award to the 90th Academy Awards. Mbithi began his career in advertising, and has directed ads for some of Kenya's most prominent brands. His direction of music videos has earned him recognition from local and international press such as the New York Times, Fader, and Huffington Post and was also highlighted by Google during the launch of YouTube Kenya. Mbithi has also been a part of the highly acclaimed experimental art collective 'Just a Band' and has currently signed on to direct, The Czar, a political thriller based on Michela Wrong's best-seller, 'It's Our Turn To Eat'. More recently, he was part of the writers room for Ink Factory for an international thriller series based between the UK and Kenya and his short film, Baba, had its world premiere at TIFF 2022 and screened at the 2023 International Film Festival Rotterdam. He is currently developing several original feature film and series concepts.