The news comes two days after The Iron, currently lying 16th in the third tier, were thrashed 5-0 at Blackpool, with assistant David Kelly also departing Glanford Park.
A club statement on Monday morning said: "Scunthorpe United Football Club have terminated the contracts of manager Mark Robins and assistant manager Ned Kelly with immediate effect."
Scunthorpe chairman Peter Swann said: "We are sad to part company with Mark and Ned, but we have to think about the best interests of Scunthorpe United Football Club.
"We wish Mark and Ned all the best for the future."
Saturday's result meant Scunthorpe had won only one of their last seven league matches and they are six points clear of the relegation zone.
Robins had been in the job since October 2014 and last season guided the club - second-bottom when he took over - to a 16th-placed finish.
The 46-year-old former Manchester United striker had previously managed at Huddersfield, Coventry, Barnsley and Rotherham.
Source : PA