James was making his first competitive appearance for the Blues since another knee injury suffered against AC Milan in the Champions League back in October.
That injury ruled James out of the FIFA World Cup in Qatar, where England bowed out at the quarterfinal stage to France.
The 23-year-old had stepped up his recovery during that enforced break but lasted just 52 minutes on his comeback before getting hauled off for Cesar Azpilicueta as Chelsea claimed a 2-0 win against the Cherries.
A statement on Chelsea's website read:"Defender Reece James underwent assessment earlier today after being substituted during the second half of last night’s 2-0 Premier League victory over AFC Bournemouth due to a knee injury.
"Scan results have regrettably confirmed a setback for the 23-year-old, with Reece now set to be ruled out for up to a month."
Reacting to his latest setback, James posted on Twitter: "2022 has been the toughest year to date."
"Just wanna thank you all for the support, none of you go unnoticed.
"It's naturally [affected] me mentally, I'm currently just [trying to] deal with the cards I've been dealt.
"I hope your end of year is filled with peace, joy happiness."
James has played 12 times for Chelsea this season, scoring two goals and providing two assists.
