The 35-year-old said the fact that he wanted his kids to remain in the United Kingdom for another year made it impossible for him to return to South Africa on a permanent basis.
"Last season I was almost close to joining Orlando Pirates, but it didn't happen," Pienaar told the media.
"The reason the move to Pirates didn't happen is that my kids were still in school in the UK, and I wanted them to stay for another year," he explained.
Pienaar said he heard of Wits' interest in his services upon his return to South Africa following the expiry of his contract with Sunderland in June 2017.
The former Bafana Bafana skipper recalled how he bumped into Gavin Hunt at the SuperSport TV studios.
After his conversation with Hunt, the veteran midfielder knew that he would end up at the Braamfontein-based club.
"When I came back my agents spoke to a few clubs. They told me about Wits. When i bumped into the coach, that made my decision easy. I bumped into Gavin Hunt at the SuperSport studios. He first spoke to my brother. Then my brother said 'I will let you two talk'," recalled Pienaar.