The former 'Scrubs' star will play a major recurring role in the crime drama, opposite lead actor Rainn Wilson, reported Fox News.
She will play Amy Gazanian, a journalist and Backstrom's (Wilson) ex-fiancee.
"When we first began our search for this crucial character we all agreed that we needed someone like Sarah Chalke," executive producer Hart Hanson said.
"Imagine our glee when we actually scored the person most like Sarah Chalke in the world - Sarah Chalke!"
The series was picked up by Fox after originally being rejected by CBS.