Mr Mulholland, who leads the prosecution service, has informed the government he will leave the post after five years following May’s election.
He said the Crown’s expertise in dealing with domestic abuse and serious organised crime has seen the prosecution service become “one of the most effective in the world”.
He said: “It has been a real privilege to serve as Lord Advocate, leading Scotland’s prosecution service and providing independent legal advice to the Scottish Government.
“However, after nine years as a Law Officer - the last five as Lord Advocate - I have decided it is the right time to step down and do other things.
“In recent years the Crown has embedded specialisms in the way it does its job.
“Our expertise in handling offences including rape, domestic abuse, serious organised crime, counter-terrorism and cold cases has helped us become one of the most effective prosecution services in the world and given victims greater confidence to report crimes.
“It’s been an honour to do this job working with so many dedicated and talented people to deliver justice in some of the most demanding and challenging of cases.”
First Minister Nicola Sturgeon tweeted: “Frank Mulholland has been an outstanding Lord Advocate. He has my thanks and admiration for his service to Scotland.”
The Lord Advocate has faced some criticism during his tenure, most notably over the Crown’s decision not to press charges over the Glasgow bin lorry crash.
The families of some of the victims of the 2014 tragedy are now pursuing a private prosecution against the driver.
Mr Mulholland will formally step down when his successor is appointed by the Queen.