Robinson had insisted he would not desert the club after Saturday's 3-0 home loss to Southend left MK Dons 19th in League One and winless in four maches.
Robinson was expected to lead MK Dons into a promotion battle this term, but instead the club have struggled, and the 36-year-old finalised his departure on Sunday.
"Milton Keynes Dons Football Club and Karl Robinson have today (Sunday) parted company by mutual consent," read a club statement.
Head of coaching Richie Barker will step in as caretaker manager while MK Dons seek Robinson's replacement.
Robinson became the Football League's youngest manager when taking the MK Dons helm aged just 29 in 2010, later guiding the club to the Championship.
But after just four wins in 15 league matches this term, the MK Dons bosses have moved to unseat the popular manager.
"The start to the Sky Bet League One campaign has been disappointing with results this season not matching the desired standard," the MK Dons statement added.
"Therefore chairman Pete Winkelman and Robinson have agreed it is in the best interest of both parties to go their separate ways.
"Everyone at MK Dons would like to thank Karl for his immense contribution - he will always remain a respected and significant figure at Stadium MK."
Source : PA