The former Drogheda United and Shamrock Rovers defender has opted to join the Tolka Park side for the 2013 season after agreeing terms
The 29-year-old centre back becomes Alan Mathews' 15th signing of the season as the Shels boss continues to build his squad for the forthcoming League of Ireland campaign.
Gartland arrives at Tolka Park from Airtricity Premier Division side Shamrock Rovers and brings with him a wealth of experience at the top level in Ireland and Scotland.
The former Republic of Ireland youth international has also had spells with Dundee United, St Patrick's Athletic and Drogheda United, where he won the League of Ireland Premier Division as well as two Setanta Cups.
He joined Scottish outfit St Johnstone in 2008, before returning to the League of Ireland in 2012 when he joined Shamrock Rovers.