Clarke's fellow New Zealander Jake Heenan will also make his first start for Connacht on Saturday. The 21-year-old former Baby Blacks captain comes into the back row at blindside flanker with John Muldoon moving to number 8.
There is just one change to the backs with Fionn Carr, who missed the game against the Cardiff Blues, returning to right wing.
Speaking about the team selection and the interpro derby, Pat Lam said: "It's a big boost for the team to have Craig available to start. It's been a frustrating time for him with injury but he came through the week well and is raring to go.
"Jake made a big impact coming off the bench in the last two games and his selection gives us an energetic back row, while Fionn trained well this week and returns to the wing.
"We're all really looking forward to the first interprovincial game where both the teams and supporters will bring a lot of passion to the Sportsground."
While the Clan Terrace is now sold out for Connacht v Ulster, tickets for the Main Stand are available online from tickets.ie, from the Connacht Rugby office, and from Centra and SuperValu stores province-wide.
Tickets bought from the Connacht Rugby office are €25 for adults and €5 for children (aged 4 to 17). For a full list of ticket prices, please click here.
CONNACHT (v Ulster): Gavin Duffy; Fionn Carr, Robbie Henshaw, Eoin Griffin, Matt Healy; Dan Parks, Kieran Marmion; Brett Wilkinson, Jason Harris-Wright, Nathan White, Michael Swift (capt), Craig Clarke, Jake Heenan, Willie Faloon, John Muldoon.
Replacements: Sean Henry, Rodney Ah You, Ronan Loughney, Aly Muldowney, George Naoupu, Paul O'Donohoe, Craig Ronaldson, Danie Poolman.