The Red Devils have not won in seven League One matches but had drawn their last three and currently lie a respectable 12th in League One.
A club statement read: "Crawley Town Football Club can confirm that it has terminated the contract of first-team manager Richie Barker with immediate effect.
"The club will make an announcement as soon as possible on who will look after team affairs in the interim period and we ask our supporters to have patience while the process of finding a new manager is undertaken.
"The club will not be making any further comment at this stage."
Barker, 38, moved from Bury to become Crawley manager in August last year and guided the West Sussex club to 10th last season.