Former Tottenham midfielder Mason signed a day before the closure of the transfer window as a summer of pursuit for the England international ended in a club-record £12.5m deal.
"The club has shown a lot of faith in me and hopefully I can repay that with some good performances," said Mason to the Hull Daily Mail.
"I've been at a very big club and played in European games and I put pressure on myself to perform week in and week out. It will be no different here.
"It is a big fee, but I am sure I can do enough to justify that."