The 27-year-old player, who was released by Amakhosi last month, has signed a three-year-deal with the Team of Choice following a successful trial at the KwaZulu-Natal club.
Buchanan will look to prove to himself as a key asset for Fadlu Davids' side in the middle of the park.
The midfield maestro is hoping to resurrect his career at the Team of Choice following a frustrating spell with Chiefs.
“It’s a new start for me and I’m excited to be here. It’s a good team, a good coach, good supporters and structures, and a good style of play,” Buchanan told the club's official website.
“I will be doing my best to try and add to a team which has much quality and who enjoyed a very good season last season," he continued.
“Coach Fadlu is one of the main reasons I have joined the club,” Buchanan continued.
“The way his team plays, the style of coaching, the fact that he knows what I can do and where he can improve me, so I am very excited about that," he said.
Maritzburg head coach Davids is looking forward to having at his disposal the qualities that the Cape Town-born midfielder brings.
“I think Keagan will give us a different dimension in midfield, he will complement well our playing style,” he said.
“He has to adapt to our playing style, but that will come with time and that’s why he has been here since the start of pre-season," he continued.
“I know Keagan because I worked with him at Bloemfontein Celtic. I know what type of character he has and that he would fit well into our dressing room environment," the retired striker added.
"I think he’s settling in very well and will bring us that extra quality in midfield," he concluded.