Mtsweni is joined by former Bidvest Wits defender Tebogo Moerane in the Usuthu books.
Both players have signed two-and-a-half-year deals with AmaZulu after a short assessment with the KwaZulu-Natal club.
“I’m here to work, and I’m happy because I feel at home,” Mtsweni told the club’s official website.
“We’re going to do our best to make the supporters happy by taking AmaZulu to where they belong,” added the defender.
Moerane is excited at the prospect of furthering his career with Usuthu this season after playing 15 games for Wits last season.
“I’m happy I can get a chance to play again at AmaZulu. I was welcomed very well by the senior players, and I feel at home,” said the SA U23 international.