Of the four terminated employees, the CSC said two were correction officers and two were correctional managers.
Edmonton police are also looking into possible criminal charges as a result of behaviour at the maximum-security prison.
A news release Tuesday said several staff were suspended last September while the Correctional Service brought in investigators to look into the claims.
Additional disciplinary hearings are pending.
“We are committed to holding employees accountable for their actions,” Commissioner Don Head said in the statement.
“We are determined to improve the workplace to ensure all employees have the respectful work environment they deserve so they can perform the difficult task that they have each and every day.”
James Bloomfield with the Union of Canadian Correctional Officers said he represents both accused and victims in the case and can’t comment further until all investigations are complete.
“We’re ensuring our members are moving their workplace to an environment that’s better than what it is today.”
A workplace assessment completed last year by investigation company TLS Enterprises described the prison as a toxic environment and made dozens of recommendations for change. One of those recommendations called for a new warden and management team, according to the CSC.
The CSC said the former warden was not the subject of allegations in this investigation.
The Correctional Service said it has already increased training and created a confidential tip line for employees to report misconduct.
It said new leadership will bring in further measures. Gary Sears was appointed this week as the new warden at Edmonton Institution and France Gratton takes over as regional deputy commissioner for the Prairies.
With files from Global News.