Bollinger, 25, is currently enjoying an excellent season with New South Wales having claimed 22 wickets in five Pura Cup matches at an average of 24.68.
He joins fellow NSW star Phil Jaques at Worcester as the county's second overseas player.
Steve Rhodes, the county's director of cricket, said: "We have been looking for a left arm fast bowler to give balance to our attack who is available for the whole season. Doug fulfils all those criteria, has a strong work ethic and is currently enjoying an excellent season with New South Wales.
"I have personally spoken to both Phil Jaques and Glenn McGrath and they speak very highly of him. Our success last season was a result of our strong team ethic and everything I have heard about Doug leads me to believe he will fit in superbly."
"I have heard a lot of good things about Worcestershire and am really looking forward to joining Phil Jaques and the rest of the team at New Road in April. This is a great opportunity for me to progress my career and I can assure all the Worcestershire supporters that they will get 100 percent effort from me," said elated Bollinger.