Leimer, who started the season as the reserve driver for Amlin Aguri, has been drafted in the place of Jaime Alguersuari.
Virgin still has a mathematical chance of clinching the drivers' title with Sam Bird, and is in a tight three-way battle for fourth place in the teams' championship together with Dragon Racing and Andretti.
Leimer has experience of the Spark-Renault SRT_01E, having driven for Amlin Aguri during pre-season testing at Donington.
Fabio Leimer said: "As a racing driver, I love a challenge and so joining Virgin Racing for the Visa London ePrix will be a great test. It's going to be an incredible and unique experience racing on the London street circuit and an even more special occasion racing for a new team in their home race. I'm looking forward to racing alongside Sam and hopefully contributing to a successful season finale for the team."
Alex Tai, the Team Principal of Virgin Racing, added: "We are delighted to have a driver of Fabio's quality and experience join the team for the final race of the season in London. This weekend promises to be a fantastic end to a great championship and so we're looking forward to seeing Fabio and Sam finish the season for the team in style."
FIA Formula E