Bopara, 28, will take the place of compatriot Chris Tremlett while the fast bowler is on Ashes duty, and becomes the third England international to sign for the Sixers with batsman Michael Lumb also on the books.
Essex star Bopara, who has played 13 Tests, 94 ODIs and 26 T20 internationals, said: "I'm delighted to be joining the Sydney Sixers for the first half of the Big Bash.
"The Sixers are famous throughout the cricketing world and I'm privileged to have the opportunity to represent them. The team is full of absolutely fantastic talent and I'm looking forward to catching up and playing alongside them when we meet up next month."
Sixers general manager Dominic Remond said: "Ravi fills a great role for us at the Sixers as an all-rounder with excellent stroke play and medium pace bowling. He has played at the highest level of international cricket and will bring great experience to our team."
- Sports & Recreation
- Sydney Sixers
- Michael Lumb
- Chris Tremlett