Contracts for the ownership of the networks will be worth almost £400 million (EUR 489 million), Ofgem said.
Both projects are situated in the North Sea off the coast of Yorkshire in the north east of England.
The competitive tender process will result in an owner being appointed for each project, with a licence granted to own and operate the transmission assets.
In return, both owners will receive a guaranteed revenue stream for 20 years.
Ofgem said that in order to make the tendering process simpler and quicker it has decided to combine the pre-qualification and qualification into one enhanced pre-qualification stage.
Developer E.on has started work on installing the foundations for the Humber Gateway wind farm, with the project due to go online in 2015. Also expected to be commissioned next year, Westermost has had some foundations installed by developer Dong Energy.