Hornacek, who had a 14-year career as an NBA player and recently served as an assistant with the Utah Jazz, will sign a three-year deal as early as Sunday night to join the Suns, according to sources.
The 50-year-old Hornacek also had interviewed for the vacant Charlotte Bobcats head coaching job. However, the Suns began negotiating a deal Sunday with Hornacek, who has maintained a home in the Phoenix area.
A fan favorite as a Suns player, Hornacek will attempt to help Phoenix rebound from one of the worst seasons in franchise history.
The Suns are coming off a last-place finish in the Western Conference at 25-57, the fourth-worst record in the NBA and second-worst in franchise history behind a 16-66 effort in their inaugural season of 1968-69.
Interim coach Lindsey Hunter went 12-29 after taking over in January for Alvin Gentry, who was fired in his fourth season with the Suns.
The Suns dismissed general manager Lance Blanks last month. Blanks had served as general manager since August 2010.
Hornacek played the first six seasons of his NBA career in Phoenix after being picked in the second round by the Suns in the 1986 draft. He averaged a career-best 20.1 points per game in 1991-92, a season in which he made his lone All-Star appearance. It was also his final season in Phoenix as he was traded before the following season to the Philadelphia 76ers in a deal that brought Charles Barkley to the Suns.