The news follows Vivendi and News Corp's decision earlier this year to merge their loss-making Italian pay-TV services Telepiu and Stream.
The Polish deal will see the creation of a business with 700,000 subscribers called TKP. It will be managed and 75% owned by Vivendi's pay-TV unit Canal+. UPC will hold 25% of the company and receive €150m (£94.1m) in cash.
Vivendi is also working on an agreement to merge its Spanish operation Sogecable with Telefonica's Via Digital.
Canal+ is coming under increasing pressure from Vivendi CEO Jean-Marie Messier to meet cost-saving targets of €400m (£250.9m) a year from 2002, following its takeover of Seagram for €42.3bn (£26.8bn) last year.