The 24-year-old loosehead prop has exercised an option to play overseas on a sabbatical and will link up with Richie Murphy's side in early December.
Bell made his Australian test debut just after his 20th birthday against New Zealand and has gone from strength to strength.
A unique profile of a prop, Bell is an athletic, physical, agile front rower, standing at 194cm and weighing 125kg. He has adapted his game after playing in the backrow in his school rugby days.
A natural leader, Bell was the captain of the Junior Wallabies team that were narrowly defeated by France in the 2019 World Rugby U20s Championship Final in Argentina.
He would go on to be a mainstay of the Waratahs side in Super Rugby, recently making his 50th cap for the team in April.
Bell has made 36 appearances for the national side, including test appearances in the Rugby Championship and the 2023 Rugby World Cup.
"I'm very excited to be joining Ulster Rugby later this year and experiencing the game in a different hemisphere," the Australian told the Ulster Rugby website.
"A big motivation for me was wanting to develop my game in a brand-new environment and be out of my comfort zone. My conversations with Bryn about that only made me more excited to join such a historic club.
"I've heard a lot about the supporters and their passion in following the team both home and away. I'm looking forward to linking up with the players, coaches and staff and can't wait to meet you all as an Ulster player!"
Meanwhile, Ulster Rugby's General Manager Bryn Cunningham is excited about the clubs' high-profile signing.
"We are delighted to secure a player of Angus' talent for next season," said Cunningham.
"We have always said that we would look for opportunities in the market to add players who can make a big impact in our team and Angus definitely fits that bill. He is at an excellent age profile and is currently one of the most exciting loosehead props in world rugby.
"Consistently topping the stats for props in metres made, defenders beaten, and number of carries only highlights the power and athleticism Angus possesses. He will be a great addition to our forward pack, giving us additional firepower, and I know that Jimmy Duffy and the coaching staff are very excited to work with him when he joins.
"Richie has been working hard to improve the competitiveness within the squad and Angus will add to the standards and help drive that competition for minutes next season."
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