Winger Cooper Vuna has signed for Bath until the end of the season, when prop Victor Delmas will join from French second-tier club Colomiers.
Meanwhile, Samoa international Anthony Perenise, 35, has agreed a new contract with the Premiership side.
BBC Radio Bristol reports Vuna, 30, will act as cover for injured England back Semesa Rokoduguni, who is recovering after shoulder surgery.
Vuna played in 31 Premiership games for Worcester between 2015 and 2017.
"To be able to bring in a player of his calibre at this stage of the season is a real boost for us," director of rugby Todd Blackadder told the club website.
Vuna, who has been capped at senior international level by both Australia and Tonga, added: "I am really excited that the opportunity to join Bath has come up.
"There is a lot to play for, and I am looking forward to getting out there on the pitch and making a difference when I get an opportunity."
Delmas, 26, added: "It's a great opportunity for me to play for one of the biggest clubs in England, but also continue my development as a player."