They swam out from the shore at Coney Beach at about 20:20 BST on Friday after the man was thrown from the water bike.
The man, who suffered a leg injury, was checked by paramedics but did not need hospital treatment.
Milford Haven Coastguard said both Porthcawl RNLI lifeboats were launched.
Two members of the public have rescued an injured jet skier from the sea off Bridgend county.