Johnson, an Arizona native who now attends Henderson (Nev.) Findlay Prep, verbally committed to Sean Miller's program Wednesday evening.
Johnson, the nephew of NBA Hall of Famer Dennis Johnson, confirmed the news to Scout.com.
"I woke up today and talked to my dad and he just reassured me that him and my mom will be behind me no mater what decision I make," Johnson said.
Visits were also set up to Louisville and Kansas, but Johnson, a 6-foot-3 guard, went with the school that had been atop his list from the beginning.
"They had been my favorite the whole time and I just felt like the time was right," he added.
Johnson is Arizona's second 2011 prospect to commit to Miller. He joins 6-foot-8 big man Sidiki Johnson to make up their current recruiting class.
Nationally Johnson is ranked as the No. 42 prospect and he checks in at No. 14 on the shooting guard list.