Our research found that the shedding of microplastic fibers (MPFs) from textiles is exacerbated by repeated mechanical recycling, raising environmental concerns as the use of recycled fibers increases in industry. This study examined MPF release from fabrics containing 30% mechanically recycled polyester fibers subjected to one, two, or three recycling cycles, compared to primary (virgin) polyester (PES). Shedding was assessed under both simulated wear and laundering conditions using Martindale, ICI Pilling Box, and ISO 4484–1:2023 (microplastic from textile sources) protocols. Laundering tests showed no clear difference in MPF release between primary PES and once-recycled PES (rPES-1; ∼ 1.4-fold). In contrast, fabrics with fibers recycled twice (rPES-2) and three times (rPES-3) released about 4.3-fold and 6.2-fold more MPFs than PES, respectively. Fiber release was different under dry-state abrasion than in laundry tests, highlighting the limitations of current wet-state focused assessments. Progressive fiber fragmentation and increased yarn hairiness suggest cumulative structural degradation with each recycling cycle. These findings underscore the need for standardized dry-state shedding assessments and improved recycling strategies to mitigate MPF emissions. While mechanical recycling remains environmentally preferable to uncontrolled disposal, these findings reveal a trade-off in the form of increased MPF release after multiple recycling cycles, which could be mitigated through improved recycling processes and fabric design. Achieving a balance between textile circularity and environmental sustainability remains a critical challenge for the industry.