The 44-year-old talk show host proposed to his long-term girlfriend Molly McNearney while holidaying in South Africa`s Kruger National Forest, his representative has confirmed.
Jimmy and 34-year-old Molly - who is a co-head writer on her partner`s show `JimmyKimmel Live` - began dating in October 2009, a few months after he split from comic Sarah Silverman after a five-year romance.
A source said when they first got together: "After Jimmy and Sarah [Silverman] broke up, Molly and Jimmy both found themselves single, and they clicked. They`re really happy together."
The TV star has children Katie, 21, and Kevin, 19, with first wife Gina, who he married in June 1988 and split from 14 years later.
The marriage will be Molly`s first.
The happy news proves Jimmy`s personal life is going as well as his career as it was recently announced he is to host the Emmy Awards for the first time.
Referring to actor Eddie Murphy - who pulled out of hosting this year`s Academy Awards - Jimmy said: "I hope to be able to do for the Emmys this year what Eddie Murphy did for the Oscars."
The 64th Primetime Emmy Awards will take place at Los Angeles` Nokia Theatre on September 23.