International clinical practice guidelines for low back pain (LBP) contain consistent recommendations including universal provision of information and advice to remain active, discouraging routine referral for imaging, and limited prescription of opioids. This systematic review describes usual care provided by first-contact physicians to patients with LBP. Studies that reported the assessments and care provided to people with LBP in family practice and emergency departments (EDs) from January 2000 to May 2019 were identified by searches of PubMed, EMBASE, and CINAHL. Study quality was assessed with reference to representativeness of samples, potential misclassification of patients, potential misclassification of outcomes, inconsistent data and precision of the estimate, and the findings of high-quality studies were prioritized in the data synthesis. We included 26 studies that reported data from almost 195,000 patients: 18 from family practice, and 8 from EDs. Less than 20% of patients with LBP received evidence-based information and advice from their family practitioner. Around 1 in 4 patients with LBP received referral for imaging in family practice and 1 in 3 in EDs. Up to 30% of patients with LBP were prescribed opioids in family practice and up to 60% in EDs. Large numbers of patients who saw a physician for LBP received care that is inconsistent with evidence-based clinical practice guidelines. Usual care included overuse of imaging and opioid prescription and underuse of advice and information. Suboptimal care may contribute to the massive burden of the condition worldwide.