The untitled project will star Silverman as a woman readjusting to being single after a decade spent in a relationship.
Lost star Leung will play a neighbour and love interest for Silverman's character, according to TVLine.
Described as a "shut-in", Leung's character spends most of his time watching TV in his apartment.
The actor played Miles Straume on Lost from 2008 to 2010 and has since appeared in an episode of The Good Wife.
His additional credits include episodes of the The Sopranos and Law & Order and film roles in 2004's Saw and 2006's X-Men: The Last Stand.
Harris Wittels and Party Down actress June Diane Raphael previously joined the cast of Silverman's pilot.
The project landed at NBC in August after reportedly sparking a bidding war between the television networks.
Roseanne Barr's Downwardly Mobile, The Munsters reboot Mockingbird Lane and a remake of UK sitcom Friday Night Dinner are among the other comedy projects in the works at NBC.
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