Steven Metcalf's 21-seat Screen Room in Hockley is one seat smaller than its main rival, the Terrace Theatre in Tinonee, Australia.
The tiny cinema opened on Friday in a former jeweller's shop close to Nottingham's famous Lace District.
The first film screened at the cinema was Lost in La Mancha starring Johnny Depp.
Pink radiators
Mr Metcalf said he wanted to make his mark and having the smallest cinema seemed a good way to do it.
"My brother saw this place and knew I was looking for a place to open a cinema, so we thought why not beat the world record."
He says he intends to contact the Guinness World Book of Records to confirm the cinema is the world's smallest.
Mr Metcalf already runs The Electric Cinema in Birmingham, which has two screens catering for 100 people, and has been involved with cinemas for 20 years.
The Screen Room is so small it uses a rear projection system to save space and does not allow popcorn because it might disturb film-goers.
The auditorium is 15ft by 15ft and has a 10-feet-wide screen.
"I wanted to make it a little different, so the walls are blue, the radiators are pink, and the skirting boards are yellow and the seats red."
The cinema features art and cult classics, but also has mainstream films.
The smallest cinema in Wales has 23 seats and is located in a railway carriage in a back garden in Gorseinon.