Coach Abdeslam Ouaddou had expressed concern in recent weeks for a lack of cover in that position and said too much of a workload for first-choice Kamogelo Sebelebele could see him burn out.
Sigomoshe, 26, made his professional debut with Milford FC in the 2023/24 season and was largely a regular ever since.
He made 88 appearances (51 starts) and scored 12 goals, having also featured as a right winger. He played in four games this season (three starts), missing the opening 2-0 loss to Pirates in the league.
“Orlando Pirates Football Club is pleased to announce the signing of Bulelani Sigomoshe from Milford Football Club,” Pirates said in a statement. “The 26-year-old right-back joins the Buccaneers with immediate effect, adding further depth and competition to the Club’s defensive options.
“Sigomoshe’s acquisition forms part of the Club’s ongoing efforts to strengthen the playing squad as the Buccaneers continue to pursue their objectives across all competitions.
"The defender will link up with the technical team and his new teammates immediately as he begins the next chapter of his career in the famous black and white.”
Pirates are next in action away at Marumo Gallants on Sunday.