However, the deal might not materialize as Premier Soccer League (PSL) giants Kaizer Chiefs are said to have registered their interest in the 19-year-old player.
According to a source, who spoke to The Citizen, Mtshali will have the final say regarding his future as Kings are open to selling him.
“There are just a few details to iron out in the Highlands Park move as almost everything has been done,” the source said.
“Chiefs have just come in and shown interest and while some of his friends are trying to convince him to go to Naturena," the source added.
"He is not too keen after what happened to him at Orlando Pirates,” the source concluded.
Mtshali was released by Pirates prior to the start of the current season having failed to break into the star-studded Bucs starting line-up
It is said that the promising midfielder is cagey about joining a big team now because of his unsuccessful spell with the Buccaaneers.
Pirates signed Mtshali and Siphelele Zikalala from Kings at the end of the 2015/16 campaign with the two midfielders having impressed during the ABC Motsepe League play-offs.
Despite being only 18-years-old, Mtshali was named Player of the Tournament after playing an instrumental role in helping Kings clinch promotion to the National First Division (NFD).
The teenager spent the 2016/17 season on loan at Kings from Pirates and he made scored four times in 25 matches. He returned to Kings after being released by Bucs.
Mtshali has been one of KwaZulu-Natal side's best players this season as they look to clinch promotion to the PSL. He has made 16 appearances in the league thus far and netted three times in the process.
His form is said to have attracted interest from NFD log leaders Highlanders and Pirates' fierce rivals Chiefs ahead of the next transfer window which will open in July 2018.