Tinkler will be officially unveiled as the new assistant coach of Pirates by the club's chairman Irvin "Iron Duke" Khoza at training today.
"I can confirm that Eric is joining us as an assistant coach, I was approached by the coach (De Sa) that he would like to work with Eric," Khoza said yesterday.
"I immediately spoke to Brian Joffe (the chairman of Wits), he agreed to release Eric to come and join Pirates with immediate effect.
"We have a solid working relationship with Wits, which goes a long way. I would like to thank Mr Joffe for the gesture.
"The appointment of Eric is yet another vote of confidence by Pirates' management of former professional soccer players of South Africa to coach the team.
"Just like Roger, Eric also has a passion for development, which is why the duo were doing well with youngsters at Wits. I strongly believe we have a great technical staff to ensure that we continue winning trophies again. We also need to do well in the African Champions League."
De Sa is likely to retain Pirates legend Tebogo "Tebza Ngwana" Moloi with Siphiwe Ngwenya set to return to the club's development programme.
When De Sa was employed as coach two weeks ago, Khoza made it clear the former Bafana Bafana goalkeeper would have a free hand in choosing his own assistant.
"That is the reason why I have gone to Wits to negotiate for the release of Eric because the two coaches have worked together for a long time," said Khoza.
Tinkler looked lonely on the Wits bench after the arrival of Spaniard Antonio Lopez Habas, who replaced De Sa in August.
Habas, who has also worked at Mamelodi Sundowns, also brought along his long-time friend Miquel Martinez to serve as his assistant.
De Sa and Tinkler could not be reached for comment at the time of going to press.