STUDY DESIGN.Retrospective cohort. OBJECTIVE.We evaluate the correlation of the Patient-Reported Outcomes Measurement Information System for physical function (PROMIS-PF) with legacy patient-reported outcome measures (PROMs) in patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) up to 2 years postoperatively. SUMMARY OF BACKGROUND DATA.PROMIS-PF has not been validated past 6 months following MIS TLIF. METHODS.A surgical registry was retrospectively reviewed for eligible MIS TLIFs between May 2015 and September 2017. Inclusion criteria were primary, one- or two-level MIS TLIFs for degenerative spinal pathology. Patients without preoperative or 2-year follow up PROMIS-PF surveys were excluded. Demographic, perioperative, and PROMs including Visual Analog Scale (VAS) back, VAS leg, Oswestry Disability Index (ODI), 12-Item Short Form (SF-12) physical component summary (PCS) scores, and PROMIS-PF at preoperative and postoperative timepoint (e.g., 6 weeks, 12 weeks, 6 months, 1 year, and 2 years). A paired t test evaluated PROM improvement from baseline. The relationship of PROMIS-PF with VAS back, VAS leg, SF-12 PCS, and ODI was evaluated with a Pearson correlation coefficient. RESULTS.The 68-subject cohort was 41.2% female, with an average age of 52.9 years; 44.1% were obese, and the majority underwent one-level fusions (95.6%). Pain (VAS back, VAS leg) and disability metrics (ODI) demonstrated significant improvement at all timepoints following MIS TLIF when compared to baseline (all P < 0.001). Physical function (SF-12 PCS, PROMIS-PF) demonstrated significant postoperative improvement at 12 weeks, 6 months, 1 year, and 2 years (all P < 0.001). All evaluated timepoints, with the exception of preoperative VAS back scores, revealed strong PROMIS-PF correlations with VAS back, VAS leg, ODI, and SF-12 PCS. CONCLUSION.PROMIS-PF demonstrated a strong correlation with pain (VAS back, VAS leg), disability (ODI) and physical function (SF-12) at all postoperative follow-ups through 2 years. Our study provides longitudinal evidence for utilizing PROMIS-PF as a valid physical function measure among patients undergoing MIS TLIF.Level of Evidence4.