Jeje has signed a new three-year deal while Karanjit has penned a two-year extension.
"We are very happy to have retained Jeje and Karanjit. Jeje has been with the club since its inception and has grown into a leader and of course become one of the finest players of the country," said Chennaiyin FC co-owner Mrs Vita Dani.
She added, "Ever since we have picked Karanjit in the 2015 ISL auction he has shown grown great commitment and consistency. The great thing is both are yet to reach their peak so we look forward to many more great seasons from the two."
Jeje, who won the ISL Emerging Player Award in 2015, is Chennaiyin's all-time second highest scorer and ISL's all-time highest Indian scorer with 13 goals in 27 starts.
Karanjit has made 13 appearances for Chennaiyin so far with four clean sheets.