The Bucks landed on Griffin as their choice Saturday morning and began negotiations on a multiyear contract that is expected to result in a formalized deal soon, sources said.
Bucks general manager Jon Horst and team ownership became sold on Griffin's leadership presence, character and ability to oversee high-level defensive teams, sources said.
Griffin will replace Mike Budenholzer, who was dismissed after five years following a first-round playoff loss to the Miami Heat. Griffin will take over a franchise that has had significant success in recent years around two-time MVP Giannis Antetokounmpo and is only two years removed from winning the NBA title.
Each of three finalists for the job -- Griffin, Golden State Warriors associate head coach Kenny Atkinson and former Raptors coach Nick Nurse -- met with Antetokounmpo as part of the search process, sources said.
Griffin, who spent the past four years as Nurse's top assistant in Toronto, is getting his first head-coaching job and comes with a reputation as a high-level defensive coach. He built his defensive system under Scott Skiles, Tom Thibodeau, Billy Donovan and Nurse. Griffin also built a reputation for his player development, which included his work with Jimmy Butler and Pascal Siakam.
Griffin has history with Horst, who was in the front office when Griffin started his coaching career in Milwaukee in 2008. A steady climber as a top head-coaching candidate among the pool of league assistants, Griffin also had stops with Oklahoma City, Orlando and Chicago.
Griffin played parts of nine seasons in the NBA, including stops with Boston, Dallas, Chicago, Houston and Seattle. He started eight games in the playoffs during the Mavericks' NBA Finals run in 2006. He was also voted MVP in both the Continental Basketball Association and United States Basketball League.