The Omnicom Media Group agency won the business from Equinox, the sister agency of ZenithOptimedia, without a pitch.
Equinox had been the incumbent on the business for ten years and had defended it successfully last year in a pitch against Maxus and Vizeum. However, a shake-up in the MTV marketing department led to another review.
PHD's remit will cover communications strategy and buying across MTV's UK channels, including the recently launched Viva.
The agency will work alongside MTV's creative shop, Quiet Storm, and Matt Sanders, who was recently promoted to managing partner at PHD, will run the business.
Zoe Harris, the marketing director at MTV, said: "PHD demonstrated both rigour and creativity in their approach and we're looking forward to adding their thinking to our plans alongside Quiet Storm."
MTV Networks operates ten wholly owned channels in the UK, including MTV, MTV Hits, VH1 and Viva.
The Comedy Central and Nickelodeon channels in the UK operate as part of a joint venture between MTV Networks International and BSkyB. Sky also handles advertising sales for MTV Networks following a recent deal that saw its Sky Media commercial unit win the sales contract from MTV's own Viacom Brand Solutions.
Last year, MTV launched Viva, a channel on Freeview, Sky and Virgin Media, which offers a range of content, including comedy, that goes beyond music. It replaced
the TMF channel and was a supported by an ad campaign, created by Quiet Storm, using the line: "Up your Viva!"