Opioid analgesics are commonly used for the treatment of chronic low back pain (CLBP); however, abuse potential is a major concern. This study used a randomized, double-blind, placebo-controlled, enriched-enrollment randomized-withdrawal study design to evaluate the safety, tolerability, and analgesic efficacy of an abuse-deterrent formulation of extended-release oxycodone, Xtampza ER, in opioid-naive and opioid-experienced adults with moderate-to-severe CLBP. Patients entered an open-label titration phase (N = 740); those who were successfully titrated on Xtampza ER (≥40 to ≤160 mg oxycodone hydrochloride equivalent per day) were randomized to active drug (N = 193) or placebo (N = 196) for 12 weeks. Primary efficacy results showed a statistically significant difference in average pain intensity from randomization baseline to treatment week 12 between the Xtampza ER and placebo groups (mean [±SE], −1.56 [0.267]; P < 0.0001). All sensitivity analyses results supported the primary result of the study. Secondary efficacy outcomes indicated that Xtampza ER vs placebo had more patients with improvement in patient global impression of change (26.4% vs 14.3%; P < 0.0001), longer time-to-exit from the study (58 vs 35 days; P = 0.0102), and a greater proportion of patients with ≥30% (49.2% vs 33.2%; P = 0.0013) and ≥50% (38.3% vs 24.5%; P = 0.0032) improvement in pain intensity. There was less rescue medication (acetaminophen) use in the Xtampza ER treatment group than in the placebo group. Xtampza ER had an adverse event profile consistent with other opioids and was well tolerated; no new safety concerns were identified. In conclusion, Xtampza ER resulted in clinically and statistically significant efficacy in patients with CLBP.