Tom McKenzie started with Lethbridge police in 1976 and rose through the ranks, being appointed chief in 2007.
He told the police commission that he won't seek a renewal of his contract when it expires in July.
The commission asked McKenzie to stay on the job until the end of October — an extra three months — to help put together the police budget for 2015 to 2018.
McKenzie agreed and the process to formalize his three-month extension is underway.
Under the Police Act, police commissions are responsible for appointing the chief of police.