The secretaries were suspended for allegedly disclosing the existence of a secret meeting - which took place before a Sandwell Council ethics hearing 20 months ago.
But now an independent investigation, requested by Sandwell Council, has found that the secretaries were not responsible for the disclosure and were wrongly suspended.
Chief executive David Stevens and councillor leader Yvonne Davies have issued apologises to the secretaries.
Councillor Davies told the Express & Star: "We have found that the proper procedures were not followed and the secretaries had not done anything that could warrant suspension and we have apologised.
"We are putting in recommendations on how the proper procedures should be followed in the future."
The secretaries were suspended in January 2018 after the hearing, which was into a councillor's breach of conduct, but they returned to work within a month.
The behind-closed-doors meeting took place the night before the ethics hearing into councillor Ian Jones, who removed a plot of land from a public auction.
The suspensions were made under a previous leadership when Steve Eling was council leader and Jan Britton was chief executive.
However the independent investigation was requested by David Stevens, who took over from Mr Britton after he resigned in July.
Mr Eling stepped as a councillor in May after he was suspended by Labour in January over a complaint.
Councillor Davies added: "I would be absolutely blown away if a decision to suspend the secretaries could be made without discussing it with the leader. I would be extraordinary and unbelievable if the leader was not informed of the impending actions."
Mr Stevens told Sandwell Council staff in a blog post on Friday: "As a council we didn't follow our rules which would have protected these colleagues and we left them feeling isolated and abandoned.
"Yes information that a meeting had taken place was made public and yes this caused some embarrassment.
"However the meeting wasn't held in secret and, more importantly, it wasn't the secretaries who publicly disclosed the meeting had taken place.
"Whilst this incident occurred over 18 months ago, the experience that the secretaries went through is really painful for them and so looking into the matter was a real priority for both the leader and me.
"The leader and I would like you (the secretaries) to accept our sincere apologies for the way you were treated. We have to learn lessons so this can't happen again."
At the time, the Express & Star reported that seven secretaries were suspended in January 2018. However one of the secretaries didn't go through the grievance process.
The standards hearing was into councillor Ian Jones who was found to have breached the members code of conduct for removing a plot of land from public auction.
Julian Saunders, who runs the Sandwell Skidder blog, has taken Sandwell Council to court, after the local authority failed to respond to his Freedom Of Information request into the suspensions.