The 41-year-old replaces former Scotland team-mate Graham Alexander, who was dismissed on 30 September.
Pressley was sacked by Coventry City in February after almost two years in charge, following a seven-game winless run that left them in the relegation zone.
He recently rejected the chance to talk to Scottish side Dundee United about their vacant managerial position.
Pressley has been working as a coaching for the Scottish Football Association and had just agreed to look after the Scotland Under-17 team on a one-off basis for a three-match round of qualifiers.
In a recent interview with BBC Radio Scotland, after being linked to the role at Dundee United, Pressley said: "I have built up a very good reputation in England and I have a burning desire to manage at the elite level.
"That's not an arrogance. That's a belief. In order to do that, I think you have to manage in a country like England."
The former Hearts and Rangers centre-back started his coaching career at Falkirk in 2010, leaving the Bairns three years later to take charge of Coventry.
He kept the Sky Blues in League One in his first full season in charge despite serious financial difficulties which resulted in the club being docked 10 points for going into administration.
He was fired the following year with Coventry 21st in the table, in a season when they were beaten at home in the first round of the FA Cup by non-league Worcester City.
Meanwhile, Fleetwood have confirmed that assistant manager Chris Lucketti will remain in his role, while Pressley's former Coventry assistant Neil MacFarlane has joined the coaching staff.
League One side Fleetwood Town have appointed Steven Pressley as manager.