VisitScotland gave the quality assurance grading to the visitor experience at Holyrood in recognition of exceptional customer service and high-quality facilities.
The building runs free tours for visitors explaining the history, building architecture and parliamentary process.
Scottish Parliament Presiding Officer Ken Macintosh said: “This award is a terrific achievement and a real recognition of the effort our staff put in to making the Scottish Parliament such a warm and welcoming place to visit.
“We are proud to welcome thousands of visitors each week from right across Scotland and beyond and I hope this award will encourage even more people to visit the Parliament and experience it for themselves.
VisitScotland chief executive Malcolm Roughead added: “Congratulations to the Scottish Parliament on this fantastic achievement.
“The Scottish Parliament is a truly spectacular building that offers a fantastic insight into the history and politics of our country.”