The account is currently held by Lexis, which was recently merged into sister company Text100, but is nonetheless expected to re-pitch for the business, according to a spokeswoman for The OU.
The contract is for a period of three years, with the successful agency starting work in December. The fee has not been disclosed.
The agency will be expected to promote The OU to national and regional press, consumer magazines, via radio and TV, and online.
It will also be tasked with creating and implementing a series of creative PR campaigns, events and activations, as well as promoting consumer marketing campaigns to trade press, the university said.
Interested agencies have until 23 August to request the tender documentation.
The Open University, which was founded in 1969, offers flexible, part-time study for students completing undergraduate and postgraduate courses.