Isaac Heeney, Chad Warner, James Jordon and now former Swan Nick Blakey have been under investigation since August after three women made reports of sexual assault to police.
Victoria Police confirmed on Friday morning that no criminal charges would be laid.
"Following a thorough investigation and based on legal advice, Victoria Police will not proceed with criminal charges due to insufficient evidence," police said in a statement.
The players were reportedly partying with adult entertainers in a room at the Pullman Hotel in East Melbourne on August 17 after a win against Essendon.
Slater and Gordon senior lawyer Jackson Pannam, whose firm is representing one of the women who alleges being sexually assaulted, said a police decision to not lay criminal charges does not mean an incident did not occur.
"Our client is devastated by this outcome. She reported the incident immediately, provided a formal statement and cooperated fully with the investigation. She has shown enormous courage in coming forward," he said.
"The absence of criminal charges does not prevent a civil claim from proceeding ... this outcome also sits within broader patterns of under-reporting and attrition in sexual offence matters."
Heeney, 30, welcomed the announcement and said waiting for the investigation to finish had been a difficult experience.
"The past three months have been incredibly difficult for my family, (fiancee) Steffi, and those close to me ... watching my family carrying the weight of this has been heartbreaking," he said in a statement.
"To my family and friends, your love and loyalty has meant more than words can do justice ... to those that have never doubted me, and stood by my side in solidarity, thank you."
The four players, as well as a fifth player, Riley Bice, were suspended from round 24 and the club's two finals for what the club termed a "serious breach of expected club behaviour and standards".
Those AFL-endorsed club bans were separate from the police investigation.
Civil claims are still being prepared against relevant parties.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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