The 3-1 home loss to Huddersfield sealed their fate with two games of the regular season left to play.
A club statement read: "The board of directors felt that with relegation confirmed, in fairness to both the club and Kevan Broadhurst, the time was right to terminate the appointment.
"The directors acknowledge the hard work carried out by Kevan during his time at Walsall football club and wish him every success in the future."
Mark Kinsella will take over as caretaker boss for the rest of this season.