The 27-year-old, who was a goalkeeper for the Orlando Pirates, was shot dead in his homeland after allegedly protecting his girlfriend from intruders.
"First of all, I want to express my sincere sympathy to Senzo's family and friends at this very sad time," Pienaar said via Everton's official website. "To lose your life at a young age when you have so much ahead of you is tragic and very difficult to understand.
"Senzo was a very talented goalkeeper who was well-liked by teammates and opponents alike. Our nation has lost a popular sportsman and he will be missed."
South African police are looking for three suspects.