Lieutenant-General Sir Freddie Viggers has resigned as Black Rod because of ill health, Lords Leader Lord Strathclyde said today.
Sir Freddie, 59, suffered a serious stroke on the day Parliament returned following May's general election and was rushed to hospital from his flat in the Palace of Westminster.
He missed the ceremony marking the beginning of the new Parliament and the following week's Queen's Speech and has not returned to work since.
Lord Strathclyde told peers today that Sir Freddie "continues to make a remarkable recovery from a serious illness in May".
He added: "However, I'm sure the House will respect his decision to resign which I know that he made with reluctance."
Black Rod is responsible for security, controlling access to and maintaining order in the House of Lords and its precincts.
Since May, Sir Freddie's duties have been carried out by his deputy, Yeoman Usher Ted Lloyd-Jukes, who will continue in the role until a replacement is appointed.
Lord Strathclyde said that peers will have the chance to express their "appreciation for the excellent service" Sir Freddie had given as Black Rod when his successor is appointed.
He added: "The Lord Speaker has written to Sir Freddie sending him very best wishes for a continued recovery and to his wife Jane and his family."
Sir Freddie, who took up the post in April 2009, had previously been Adjutant General until his retirement the pervious year.
The Gentleman Usher of the Black Rod is the senior officer in the House of Lords and is in overall charge of the House's administration.
The most high-profile part of the role comes on the day of the Queen's Speech, when Black Rod is sent from the Lords chamber to summon MPs from the Commons to come and hear the Queen.
When Black Rod arrives at the Commons, the door is slammed in his face to symbolise the independence of MPs from the Crown, and he knocks three times with his staff of office before being allowed in.