Having spent seven seasons in the Minors, Ngoepe would have become a Minor League free agent on Friday had he not been added to the Bucs' 40-man roster.
Ngoepe, the first black South African to sign a professional baseball contract, spent most of the past three years with Double-A Altoona, batting .229 with a .665 OPS in 274 games at that level. He was promoted to Indianapolis last season and hit .246/.313/.311 in 21 games.
Now that he is on Pittsburgh's roster, Ngoepe is protected from being picked in this year's Rule 5 Draft. He was eligible each of the past two years but went unselected.
Adam Berry is a reporter for MLB.com. Follow him on Twitter at @adamdberry. This story was not subject to the approval of Major League Baseball or its clubs.