Firearm violence has increased nationwide, with recent surges linked to the COVID-19 pandemic. We measured traumatic assault trends at our urban Level I trauma center and assessed rates of firearm violence over time and pre/post local COVID-19 lockdown based on levels of socioeconomic disadvantage. We conducted a retrospective review (2016-2022) of assault patients 16years and older. Demographics and hospital outcomes were assessed by assault mechanism (firearm, knife, blunt). Patient address was correlated to Area Deprivation Index (ADI), a measure of socioeconomic disadvantage. COVID-19 lockdown onset was defined as initial date of lockdown (3/19/2020). Trend and time-series analyses compared all assault mechanisms and firearm-specific assaults pre/post-lockdown. Poisson regression assessed firearm assault risk. Of the 1583 total assaults, firearm patients (n = 335) were younger (median 29years), had longer hospital stays (median 2days), and greater mortality (12%) than other mechanisms. The 2years post-lockdown had significantly more firearm assaults (27% vs 15% pre-lockdown, P < .001) and time-series analysis found this abrupt and significant increase in firearm assaults occurred at lockdown onset (P = .01). Also post-lockdown, the rate of firearm assaults increased by 10% for every unit increase in socioeconomic deprivation (P < .01). There was no change in assault type by race/ethnicity. Firearm assaults increased dramatically immediately post-COVID lockdown at our center and have maintained higher rates through 2022. Greater ADI was associated with increasing firearm assaults and has magnified post-lockdown, demonstrating lower socioeconomic groups are disproportionately and increasingly affected by firearm violence.