The Chiefs scored two of their three tries in the opening six minutes to take control of the semi-final in Wellington and a perfect six-from-six shots at goal from first five-eighth Damian McKenzie kept them in front.
The Blues will host the all-New Zealand final at Eden Park on Saturday after they beat the ACT Brumbies 34-20 in Friday's first semi-final.
It's a chance for one team to make amends after both lost finals to the Crusaders over the last two seasons, with the Chiefs falling short last year.
The top-qualifying Hurricanes were favoured to advance in front of their home supporters and stretch their winning streak at home to 10 matches.
However, they were rocked onto the back foot early on and couldn't recover from a 17-7 halftime deficit, with McKenzie dictacting play with his boot in general play as well as amassing 15 points.
However, the standout performer was 21-year-old Sititi, whose breakthrough performance included numerous effective charges with the ball and some thunderous defence.
The Chiefs lost fullback Shaun Stevenson to an undisclosed injury before kickoff while their All Blacks hooker Samisoni Taukei'aho limped off with a leg ailment midway through the first half.
The visitors were also twice reduced to 14 players, with Samipeni Finau shown a yellow card for a late collision in the first half and fellow-flanker Luke Jacobson sanctioned the same way for a similar offence after the break.
However, their defence largely held firm, reducing the threat of a Hurricanes attack which has terrorised defences this season.
Both were converted by McKenzie, who added a penalty before the Hurricanes got a foothold in the game, crossing through flanker Peter Lakai.
McKenzie's second penalty stretched the lead to 13 points before a high-octane Hurricanes attack ended in a try to fly-half Brett Cameron.
The match swung on an intercept from Sititi as the Hurricanes threatend to go in front, storming downfield to set up Rona's try.
A 50m penalty goal from McKenzie was followed by a Hurricanes try to Billy Proctor but the hosts couldn't pull off a miracle over the dying minutes.