Lions discard heads to Scotland
The signing of Van der Walt comes just two days before the squad departs for the Southern Hemisphere for the first time.
The 23-year-old former Lions star will join the squad before they set-off for Bloemfontein and will be available for selection immediately – having signed a two-and-a-half-year deal.
As a highly regarded youth prospect, Van der Walt progressed through the Golden Lions academy, representing the Ellis Park outfit at every possible age-grade.
The playmaker was subsequently selected in the South African Schools squad, following impressive form for the Johannesburg-based side.
Van der Walt made his senior debut for the Golden Lions during the opening match of the 2014 season and has since gone on to make 33 appearances for the 2015 Currie Cup winners, scoring 147 points in the process.
Van der Walt made his Super Rugby debut for the Lions in 2015.
The playmaker has made 22 appearances for the Ellis Park outfit and played a major role in helping the side reach this year's Super Rugby final.
"Jaco is a skilful young player who is equally adept at stand-off or fullback," Edinburgh coach Richard Cockerill said.
"He's an excellent goal kicker and will provide cover in key areas for us.
"We're delighted that he's chosen to be part of what we're building here at Edinburgh."