Hilland, an art director, joins Partizan's roster after combining his creative duties at Mother with early work for his showreel. He directed Royksopp's Eple video, along with three other short films.
As an art director, Hilland worked on Mother campaigns such as ITV Digital, Typhoo, Harvey Nichols and The Observer. Before joining Mother, he was an art editor on the launch of Conde Nast Traveller and Benetton's Colours.
Hilland, a Norwegian, graduated from St Martin's.
Kate Redvers, the directors' representative at Partizan, said: "Thomas has a reel and is at the stage when he is already very sellable. It's great when a director understands the brief and the whole process.
"Thomas designed the Mother Bible in 2000, which is brilliant and alerted him to us. There are a huge amount of things going on in his head."
Partizan, which also represents Traktor, won the Palme d'Or for the Honda "cog" spot by Wieden & Kennedy, as well as campaigns for Tango (Clemmow Hornby Inge) and the mobile phone company Xelibri (Mother).