You know, grieve your wife, this is an impulsive thing and you have no idea the kind of trouble you're getting yourself into it. And of course he doesn't listen to me and he adopts this child.

Platt won the New York Film Critics Online Award for best supporting actor for his role in Casanova. The play was set in Dublin and Platt's role was the tortured protagonist John. He also played a lard merchant named Papprizzio in Lasse Hallström's Casanova who competes with Casanova (Heath Ledger) for marriage to Francesca (Sienna Miller).

He is starring in the Showtime original series The Big C with Laura Linney.