Capela had two years left on his current contract, and he now is set to make $82 million over the next four seasons with the Hawks.
His representatives at Wasserman completed the new deal with Hawks general manager Travis Schlenk ahead of an Oct. 18 deadline for the extension.
Capela, 27, played an immense role in the Hawks' run to the Eastern Conference finals last season. He averaged 15.2 points and a league-leading 14.3 rebounds in the regular season and played well in postseason series victories over New York and Philadelphia.
He played an immense role in improving the Hawks' defense, finishing with a 4.98 defensive real plus-minus, according to ESPN's Stats & Info. He trailed only Utah's Rudy Gobert, the league's defensive player of the year, in that category.
The Hawks acquired Capela in a 2020 trade with Houston, where he had played his first six NBA seasons.