The 27-year-old will bow out from the Yorkshire-based soap later this year in order to pursue new projects.
Carter first revealed the news in an interview with Shaun Keaveny on BBC 6 Music and went on to make a number of light-hearted remarks over his character's current contribution to the programme.
He joked: "I'm getting thoroughly depressed because I'm in work every day for about four hours. It's like they're teasing me because I'm leaving and I've got one line. I'm in work every day. It's driving me mental.
"I can't even go off and meet people and talk about being King Rat in Skegness or anything like that. I can't even plan my future! They've got me by the balls."
Meanwhile, asked how Jamie will depart, Carter replied: "Why spoil the habit of my character's lifetime? It's nothing interesting - I think I just go in a cab."
An Emmerdale spokesperson this afternoon told DS: "We can confirm that after four years on the show, Alex Carter has decided to leave Emmerdale. He's been a great asset to the show and we wish him all the very best for the future."
Carter joined ITV's rural soap in November 2005 and first appeared as the local postman on February 16, 2006.