Pirates general manager Neal Huntington declined to address terms but said a deal could be reached shortly.
"It's not done," Huntington said. "There are still some things to work through. But it's close, and I'm optimistic."
Vazquez, 32, hit .290 with a .365 on-base percentage in 105 games with the Texas Rangers last season. He previously played with the Seattle Mariners, San Diego Padres, Cleveland Indians and Boston Red Sox.
Jerry Crasnick covers baseball for ESPN.com. ESPN The Magazine senior writer Buster Olney contributed to this report.