Several major organisations are already signed up to the platform, including The John Lewis Partnership, Centrica, Just Eat and British Airways.
It advocates a preventative approach, encouraging employees to nurture and take care of their own mental wellbeing with services including the Unmind Index.
The tool, which was developed by clinical psychologists, enables employees to measurably improve their mental wellbeing and target areas where support is needed.
"We're experiencing great interest in the Unmind platform. We wanted to find a partner that would help us as we scale the business," said Dr Nick Taylor, co-founder and CEO of Unmind.
Since its launch in 2016, Unmind has grown to 28 clients, providing more than 250,000 people across 47 countries access to the platform.
Nick Giles, co-founder of Seven Hills, said: "We believe that the Unmind mission is incredibly important and is transforming the way larger organisations can make a tangible improvement for their employees."
Seven Hills also works with organisations including Strava, Tech London Advocates, Level39, and Octopus Ventures.