The Ivory Coast international's current deal expires at the end of the season and he has been handed a fresh contract despite starting just twice this season.
Villas-Boas confirmed that Kalou had been given the chance to sign on with the club whilst indicating that Didier Drogba and Nicolas Anelka - also out of contract next summer - will remain loyal to the Blues.
"Kalou was offered a contract and hopefully we will continue talks," he told the club's official website.
"In January these players are available to discuss their future. We'll continue talks until we reach an agreement or not.
"The fact that they are emotionally tied to this club - like Nico (Anelka) - too, means we can count on them while they are negotiating.
"Their loyalty to the club will never be in question."