The Falcons announced the deal Friday on their official team website. Harris was the No. 22 overall pick by the Dolphins in the 2017 NFL Draft. The 6-foot-3, 252-pound pass rusher had just 3.5 sacks in 41 games in three seasons with the Dolphins.
Harris has a base salary of $1.9 million in 2020. The Dolphins had a deadline on Monday to make a decision whether they wanted to pick up the fifth-year option on Harris' rookie contract.
The Dolphins had the same Monday deadline for defensive end Taco Charlton, before they opted to waive Charlton on Thursday.
The Falcons also declined the fifth-year option for defensive end Takk McKinley on Wednesday. Atlanta selected McKinley four spots after Miami picked Harris in the first round of the 2017 NFL Draft.
Harris earned just eight starts while with the Dolphins. The Missouri product had 0.5 sack, 23 total tackles, six quarterback hits and three tackles for a loss in 14 appearances last season. Harris was linked to the Falcons before he was picked by the Dolphins in the 2017 NFL Draft.