The Warwickshire force said the officer had completed 15 years service with the police, most recently based in the north of the county.
It said he was not named as this "may risk identifying vulnerable witnesses involved with the investigation".
The sergeant was dismissed "with immediate effect for gross misconduct". There will be no criminal charges.
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It said the hearing, chaired by deputy chief constable Karen Manners, was heard in private due to the vulnerability of witnesses.
The hearing followed a professional standards investigation that started after "concerns were raised around how the officer had engaged with a number of women whilst on duty," police said.
The force said following the hearing, which ended on Monday, the police sergeant was dismissed "with immediate effect for gross misconduct".
Det Supt Gary Watson, head of professional standards, said: "The Misconduct Hearing found that the behaviour of the former Sergeant fell below the standards we expect from our officers and staff and amounted to a breach of the Standards of Professional Behaviour.
"This fell outside the expectations made clear in our Code of Ethics and it is for this reason he was dismissed."
A police sergeant has been sacked after concerns were raised around how he engaged with women whilst on duty.