The 22-year-old Kenyan player has been a member of the Sharks Academy in recent years and represented the Sharks at under-19, under -21 and Vodacom Cup level, playing in all 10 of the Sharks XV's matches in 2011, and scoring three tries.
Adongo was also part of the Sharks' Super Rugby team that played in a pre-season tournament against the Stormers and Lions in Cape Town earlier this year.
The Nairobi-born player is equally adept playing at lock or loose forward and with his express pace, also played wing for the Sharks at age-group level.
Adongo said he was excited about the move to Loftus Versfeld.
"I want to thank the Sharks for the chance they have given me to play rugby and all they have taught me about the game through the Sharks Academy, and also the senior Sharks training squad," Adongo said.
"I am very excited about my move to the Bulls. I look forward to the challenge of proving myself from scratch and it is a privilege to become part of the Union."
Adongo said he hoped to play a significant and constructive role in Bulls history going forward.
Head of Blue Bulls rugby, Heyneke Meyer, said the athletic forward should be a perfect fit.
"Dan offers a lot to any team with his size and pace and I am looking forward to see him develop and progress at the Bulls in the next couple of years," said Meyer.