Julies reported to IKamva for training on Monday morning, while Mzwakali also traveled to Port Elizabeth to join his new side.
Mzwakali, 24, leaves the Urban Warriors after four-and-a-half seasons having joined from their academy at the beginning of the 2013/2014 season.
He leaves having made 116 appearances and scored seven goals.
Julies'departure from the Chilli Boys comes as a surprise given his impressive start to life at the Teboho Moloi coached outfit.
The 26-year-old, who arrived from Mamelodi Sundowns in the off-season, recovered from a hamstring injury and came on as a second-half substitute on two occasions late in October last year and was the hero in both matches. He scored the winner against his former side Sundowns in the Telkom Knockout Last-16 just minutes after coming on and then got himself on the scoresheet twice in a 2-0 win over Bidvest Wits a few days later.
After he was released by the club in July 2016 and spent a few months without a club, the 30-year-old was recalled and signed again in November 2016.
He becomes Arrows' second signing of the January transfer window.