"It feels really good to sign a new contract for another year at the club, I'm very proud," said Hilario, who has made 39 appearances in his seven years with the Blues.
"I'm really pleased to be part of this great squad and I'm looking forward to working once again with Jose Mourinho."
Mourinho signed his fellow Portuguese back in 2006, and the former Internazionale and Real Madrid manager's return appears to have precipitated the decision to stick with Hilario.
After coming through Porto's youth set-up, Hilaro played for Naval before returning to the SuperLiga giants, where he stayed for eight years, mostly as back-up.
After two seasons at Nacional, where he was first choice, he was eventually reunited with Mourinho at Chelsea where it appears he will end his career.
Hilario made his Chelsea debut against Barcelona in October 2006, keeping a clean sheet in a 1-0 Champions League win.