The centre suffered the injury to his left foot during the first half of Bath’s 41-6 defeat at Allianz Park last Sunday.
Bath Rugby confirmed that his season is over in the last hour.
Director of Rugby, Todd Blackadder, said: “JJ is going to need surgery to correct his injury. He will then need a lengthy period of time to rehabilitate.
“Our medical team will work closely with him to ensure we get him back on the pitch as soon as possible.”
The Bath stalward has played 961 minutes for his club this season, scoring three tries in 13 games.
Capped 40 times by England and twice by the British and Irish Lions, Joseph joined Bath in 2013 from London Irish.
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