The deal, which was announced on 1 May this year, was closed this morning after receiving unconditional clearance from the European Commission.
Viacom has announced the first joint commissions between Channel 5 and its UK pay TV channels.
Viacom’s Nickelodeon is joining forces with Channel 5’s pre-school strand, Milkshake, to develop a new animated series, Nella the Knight.
The series will be produced in the UK and co-funded by the two broadcasters, who will share broadcast rights, as they already do with programmes including Peppa Pig.
In addition, Channel 5 and Viacom’s MTV UK will jointly commission a new entertainment series, 10,000 BC, in which 20 volunteers will forgo the comforts and conveniences of modern life to go back to the Stone Age.
There will be ten 60-minute episodes. These will be produced by The Garden and GroupM Entertainment to premiere on Channel 5 in 2015.
Viacom confirmed Channel 5’s advertising sales team will be retained following the closure of the deal.
Channel 5’s commercial director of sales, Nick Bampton, and its chief operating officer, Paul Dunthorne, will report separately to David Lynn, EVP managing director of VIMN UK, and join his UK senior management team, along with Channel 5’s programme director, Ben Frow.
Philippe Dauman, Viacom president and chief executive, said: "Our ownership of Channel 5 will significantly increase Viacom’s investment in British creativity and content.
"We are committed to strengthening Channel 5’s status as one of UK broadcasting’s premier brands, and we will continue to grow the network’s pipeline of original programming with more quality commissions, as well as acquisitions."
Lynn said: "Channel 5’s senior executive and sales teams continue to perform strongly and, with an innovative approach to commercial partnerships, have delivered great results.
"We look forward to working with the senior team and in-house sales staff to build on this success."