Bonar Mackenzie has been taken over by Morisons.
The expanded law firm - five partners and 18 staff are moving as part of the deal - will operate from the Edinburgh office of Morisons.
Morisons currently has nine partners in the Scottish capital and the same number in Glasgow.
Robin Valentine, managing partner at Morisons, said: "This development reinforces Morisons commitment to growth and further strengthens our business in the key areas of commercial property, employment and family law.
"We have long been impressed with the quality of the Bonar's legal team and we are delighted to welcome them aboard."
Gary Thomas, partner at Bonar Mackenzie, said: "We have always had ambitious plans for the firm and this merger enables us to accelerate that far quicker than on our own."
Earlier this year Morisons bought Macrae, Flett and Rennie.