Mr Cameron spoke of his "high esteem" for campaigners from the Korean War Memorial Committee who collaborated to design and build the monument, which is in the hills near Bathgate, West Lothian.
His praise came in a letter handed over by Scotland Office Minister David Mundell to the British Korean Veterans Association as he visited the memorial, which was opened to the public last summer to mark the 60th anniversary of the signing of the Armistice that ended the war.
Nearly 1100 British service personnel died in the three-year conflict.
In the letter Mr Cameron said: "My congratulations again for the work which you and the Trustees have done in erecting this fitting tribute to all those who fell in the conflict."
Colonel Jim Wilson, of Veterans Scotland, said: "Scotland's veterans community is delighted the Prime Minister has written to acknowledge the huge amount of work and fundraising by the members in Scotland that resulted in this moving memorial in memory of those British servicemen who died during the Korean War over 60 years ago; they gave their lives to ensure our continuing freedom."