Poster was one of the first female trainees at the William Morris Agency, where she began working in the mailroom in New York in 1986.
Poster had a producing deal at NBC Universal for five years, and served as a consultant for Chairman Jeff Zucker.
She has also developed VH1’s Mob Wives (2013) and spinoffs Big Ang (2012) and Mob Wives Chicago (2012), as well as Trailer Park: Welcome to Myrtle Manor (2013) on TLC, Rodeo Girls (2013) on A&E, Supermarket Superstar (2013) on Lifetime, Million Dollar Shoppers (2013) on Lifetime.
In addition to reality television, Poster has paired with Amy Sherman-Palladino, creator and writer of Gilmore Girls, for an adaptation of The Nanny Diaries for ABC.
She has been profiled in numerous publications, including Premiere, W, Vanity Fair, Mademoiselle, Elle, Gotham and Glamour and was ranked in The Hollywood Reporter's Power 100 for five consecutive years.