Baraclough, 41, will have only a few days to get to know his players before the season starts with a trip to face Shelbourne on Friday night.
“Timescales are not helping in terms of the league starting but there is nothing that can be done about that now and I just want to get down to work with the group of players," he told the club's official website.
“There is a keenness about the club and I think we want to show that this is where the club belongs. We want to make a massive effort to move the club further forward and bring more success to Sligo Rovers.
"The club has had a magnificent four or five years and moved to a very high level, one that I want to continue. It’ll be a tough job to carry it on but I’m determined to do it."
Baraclough replaces Paul Cook, who quit the Irish Premier Division side to take charge of English League Two outfit Accrington Stanley.
Baraclough was appointed Iron manager in September 2010, after taking charge on a caretaker basis following the departure of Nigel Adkins to Southampton.
His reign was short, however, and he was sacked following a 3-0 home defeat to relegation rivals Preston the following March in which many supporters had called for his dismissal.
In total he oversaw 34 competitive matches for the Iron, with eight wins, four draws and 22 losses.