Pain associated with chest wall trauma is a major issue in the emergency department (ED). However, it may be challenging to select among the various analgesic procedures. Our aim was to compare single-shot erector spinae plane block (ESPB) with intercostal nerve block (ICNB) under ultrasound guidance for pain management in thoracic trauma. This study was a randomized nonblinded clinical trial performed in a level I urban trauma center. A convenience sample of patients with isolated chest wall trauma and initial Numeric Rating Scale pain scores (NRS 0) > 5 were included. Exclusion criteria were large pain area, surgical interventions, discharged from the ED, and presence of contraindications to lidocaine. Pain scores at 20 min and 60 min (NRS 20 and 60) and at disposition (disp) were recorded. Twenty-seven patients in the ESPB and 23 in the ICNB groups were enrolled. Mean values of NRS 0, 20, 60, and disp for the ESPB vs. ICNB groups were 8.0 vs. 7.4, 5.2 vs. 6.1, 4.1 vs. 5.4, and 4.3 vs. 5.8, respectively (p = 0.07, p = 0.04, p = 0.001, and p < 0.001, respectively). Four patients in the ESPB and 8 patients in the ICNB groups required administration of adjunctive doses of fentanyl for satisfactory pain control (p = 0.09). Ultrasound-guided ESPB was superior to ICNB regarding pain control during the ED stay period of patients with painful chest wall trauma. We recommend ESPB in the ED for pain control in blunt or penetrating thoracic trauma.