KickOff.com confirmed a few months ago the prolific Argentinian striker was heading to Usuthu once his contract expired with Auckland City.
The 30-year-old scored a club record 107 goals in 162 matches for the Navy Blues - 41 more goals than nearest challenger Grant Young, who used to lead the line for Hellenic in Cape Town before emigrating to New Zealand.
Tade, who won a staggering 23 titles with the club after joining them in 2011, has explained how his move to Durban came about.
"The move to South Africa is something that has been in the background for the past few seasons," Tade told City's website.
"I've been in contact with an agent who has been very patient and understood me since the beginning of this process.
"I'm extremely excited and I can't wait to see what it will be like in South Africa.
"This move will be important for me as a footballer. It's a professional contract and it means a lot to me.
"Every player dreams of becoming a professional player and I'm happy and now is the time to go."
He added: "AmaZulu are very excited and I believe I can contribute something to their team in a different way that what they were used to in the past.
"The mixture of my style and AmaZulu's could be interesting for everyone concerned and we're all very excited about the possibilities."
Tade will follow in the footsteps of compatriot Emilo Gindre in joining AmaZulu, with the latter in goal when the club lost 3-0 to Bidvest Wits in the Nedbank Cup final in 2010 at FNB Stadium.
Usuthu have also added veteran goalkeeper Moeneeb Josephs and midfielder Nhlanhla Vilakazi to their roster ahead of 2018/19.