The Suns announced the move before their preseason finale at home Thursday night against the Denver Nuggets.
By forfeiting $1.2 million of his 2011-12 salary, according to the Arizona Republic, Pietrus convinced the Suns to release him outright. That will allow Pietrus to become an unrestricted free agent if he clears waivers in 48 hours.
"Lon and I have been working on this for the past few days," Pietrus' agent, Bill McCandless, told ESPN.com. "We reached a buyout agreement that's fair for Mickael Pietrus and fair for the Suns. I'm sure Mickael will have options (once he clears waivers)."
Pietrus was actually traded to the Toronto Raptors earlier this month for a conditional second-round pick, but the Raptors rescinded the trade after Pietrus' troublesome right knee was flagged during his Toronto physical.
That trade also called for the Suns to pay $1 million to Toronto and left little doubt that Pietrus no longer had a future in Phoenix. The former Golden State and Orlando swingman was acquired by the Suns as part of the December trade that brought center Marcin Gortat to the desert and created some salary-cap flexibility for the summer of 2012 through the recent release of Vince Carter.
Pietrus is expected to draw the interest from various playoff teams -- Boston, New York and the Los Angeles Lakers among them -- should he clear waivers.
The only other veteran player of note on a league list of freshly released players issued to all 30 teams Thursday, sources said, was Miami center Zydrunas Ilgauskas, who had already announced his intention to retire after one season with the Heat.
Other players with NBA experience waived Thursday as teams pare down their rosters in advance of Sunday's start to the 2011-12 season include Boston's Michael Sweetney, Cleveland's Manny Harris and the Los Angeles Lakers' Gerald Green.
Marc Stein is a senior NBA writer for ESPN.com.