22-year-old Marney played 8 times for Tottenham, which included a 5-2 win on his home debut against Everton, a game in which he scored both of his 2 goals for the club. He made a further 3 appearances in the FA Cup, and had loan spells at Swindon, QPR, Gillingham and Norwich.
Phil Parkinson told the Hull Daily Mail: "I'm very excited about bringing Dean to this club. He will give us extra legs in midfield and he is a box-to-box player.
"Dean can play on the right but his best comes when breaking through at pace in a central role and chipping in with goals."
His signing spells the end for Stuart Green, and also raises the question of where Nick Barmby would fit into Parkinson's side.
City also completed the move for Welsh international Sam Ricketts yesterday, as Swansea finally accepted to let him go for £300,000. The 24-year-old is set to become Parkinson's first choice right-back, although he can also play on the left.
The pair could make their first outings on Wednesday in City's next friendly, away to League One side Doncaster Rovers.