The comedy project - written by Traffic Light's DJ Nash - will focus on a married couple, as well as the husband's best friend and the wife's sister.
Chuck star Levi will play the husband, according to Deadline.
The actor appeared in half-hour ABC sitcom Less Then Perfect between 2002 and 2006, before playing the title role in NBC's Chuck from September 2007 to January of this year.
Let It Go was picked up to pilot by Fox earlier this month, on the proviso that it would only enter production if the network was satisfied with casting.
Levi joining the project has now lifted the contingency. The project will be executive produced with Rescue Me's Peter Tolan and 2012's Michael Wimer.
Other comedy projects in the works at Fox include John Stamos sitcom Little Brother, Prodigy Bully from Glee star Mike O'Malley and The Goodwin Games from the creators of How I Met Your Mother.
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