"Patricia Smith is a writer of extraordinary talent and this is a tragic development," Matthew Storin, the paper's editor, said in a statement.
"We wish her well and she retains many friends at the Globe, including myself."
Smith's agent and lawyer, John "Ike" Williams, said Smith had resigned on Thursday.
Smith, 42, who is also a well-known poet, did not return phone calls.
In a column being published in Friday's Globe, Smith apologises to her readers, to the paper, and to her late father, who she credits as an inspiration to her journalism career.
"From time to time in my Metro column, to create the desired impact or slam home a salient point, I attributed quotes to people who didn't exist," Smith wrote in her final column, which the Globe made available late Thursday.
"I could give them names, even occupations, but I couldn't give them what they needed most - a heartbeat.
"As anyone who's ever touched a newspaper knows, that's one of the cardinal sins of journalism: Thou shall not fabricate. No exceptions. No excuses."Reuse content