David Page and Brian Park have sold their eponymous practice to an Employee Benefit Trust.
The sale has allowed the practice's 40 employees to acquire a stake in the future of the business, founded in 1981. The two founders will remain directors of the business, which will trade as Page/Park.
Details of the transaction were not disclosed.
Mr Page, who is head of architecture, said the founders had chosen to follow in the footsteps of firms like John Lewis, which he described as trail-blazers for employee ownership.
"We have always been a very collaborative organisation so employee ownership - as well as helping us plan for the long-term, including succession - is just a logical extension of our business model," he said.
The transfer of ownership follows a successful period for the practice. It has raised turnover 30% in the past two years, to £3.5 million, in spite of tough trading conditions for architects.
Spending on private sector construction projects and housebuilding fell in the wake of the credit crunch that started in 2007.
Page and Park has worked on a range of projects including a new visitor centre for the famed Rosslyn Chapel in Midlothian.
It traded profitably in its latest financial year.
The Co-operative Development Scotland arm of Scottish Enterprise, which provided advice on the sale process, said being employee owned provided clear benefits for businesses.
"With employee ownership, all parties have a genuine say in how a business is operated, giving everyone a meaningful stake," said Sarah Deas, chief executive of the organisation.
Co-operative Development Scotland said there had been a marked increase in the number of employee-owned businesses with headquarters in Scotland since 2009.
Other employee-owned businesses in Scotland include Tullis Russell, the paper and board manufacturer, and Clansman Dynamics, which makes robots used in manufacturing.
In February last year, however, one of Scotland's most famous worker co-operatives was sold to external investors to help it pursue its ambitions.
All 105 staff at Loch Fyne Oysters voted in favour of an agreement for the Scottish Salmon Company and private equity firm Northern Link to acquire 100% of the Argyll-based business.
Bruce Davidson, managing director of Loch Fyne Oysters, said at the time the company had been looking for the right partner for around a year as the employee-ownership structure made it difficult to raise funds for expansion from external sources.
The Employee Benefit Trust has bought Page/Park under a loan agreement with the founders. The loan will be repaid from the profits generated by the company.
Baxendale, an employee ownership specialist, advised on the ownership model and related governance and employee engagement issues.