The True Blood actor will star as a failed writer who works as a dishwasher, reports Deadline.
Meanwhile, a blog called "Why You Suck", written by his ex-wife, reveals the flaws and shortcomings of Kwanten's character.
When he falls for Colette, who is marrying "the perfect man", he sets out to prove to her and the world that he is not like the man described on the blog.
Sex and Sunsets has Jeremiah Chechik as director and Megan Martin as writer, who adapted the screenplay from Tim Sandlin's 1997 novel of the same name.
Kwanten can be currently seen on True Blood, airing its fifth season on Sundays at 9pm ET on HBO.
Watch a trailer for True Blood below: