Matthews wrote on sportsjournalists.com that it was "abhorrent" the paper ran the item about a player, who was not identified but was thought by many to be Mike Piazza. Because of the buzz created by the gossip item, written by Neal Travis, Piazza publicly denied he was gay.
The Post had refused to run the Matthews' column without editing changes.
Matthews said, "I always knew the paper had no integrity," according to a posting introducing the column.
"In light of Matthews' derogatory comments and insubordination, Post management felt it was no longer appropriate for him to continue in the paper's employ," the newspaper said in a statement.
In an interview with ESPN Radio, which employs Matthews, the columnist said: "All I know is that I told them I was done writing for them."
According to the Post statement, Sports Editor Greg Gallo read the initial column and requested changes, which Matthews made. The revised column was then cleared by Editor in Chief Col Allan and had been slated to run Thursday.