Harman had been at Brackley for 17 years, having joined its engine division in 2001 as engineering leader.
He moved to the powertrain integration role with the F1 team in 2011, giving him valuable inside knowledge of how Mercedes integrated its engine systems to such dominating effect in recent seasons.
He will have the title of deputy chief designer at Enstone, assisting chief designer Martin Tolliday in the design of future cars.
"Over the past three years [chief technical officer] Bob Bell has been leading the charge for the team to reinforce its technical line-up," commented Cyril Abiteboul, managing director of Renault Sport Racing.
"We are delighted to have attracted someone of Matthew’s caliber to enable the team to anticipate on the design cycle of future cars.
"[That's] a crucial benefit, something we are currently missing since the team’s acquisition and that will become even more important with the upcoming changes planned for 2021."
The press release announcing the new hiring commented that "Harman brings a wealth of motorsport experience, most recently from his years at Mercedes AMG F1.
"In this role he ensured seamless integration between the power unit, transmission and chassis."
Renault have been rebuilding their operations since the low-point in 2015 when the team – then branded as Lotus – nearly went out of business.
Many key personnel were let go at the time. When Renault took over and made it a works team, it began the slow process of reacquiring those lost skills and expertise.
Last year Renault made waves when it signed up Marcin Budkowski for a senior management role.
Budkowski had previously been the FIA's technical officer overseeing Formula 1 and other single seater championships. Rival teams feared his knowledge of research and development across the sector would give Renault too much insider knowledge.
As a result, Budkowski's period of enforced 'gardening leave' – where he is not allowed to work with his new employers – was extended to six months. He finally arrived at Enstone in April.
It's not clear whether Harman will have a similar period on the sidelines before he's able to take up his new role at Renault.