Michael Romano, 43, managed to push his 5-year-old son out of harm's way just before he was struck around 11 p.m. Wednesday.
The driver is identified as Roderick Williams of the 3000-block of North 23rd Street.
The crash happened in the southbound outer lanes of the Roosevelt Boulevard near Loney Street in Northeast Philadelphia.
Officials say Romano was attempting to cross the boulevard with his son without a crosswalk when he was hit.
Romano was pronounced dead at the scene. The boy was treated and released at the hospital, having only suffered a cut to his ear.
Police say Williams, the driver of the striking vehicle, fled the scene. However, an off-duty police officer, who witnessed the accident, was able to pull over and arrest Williams a few blocks away.
Williams is charged with homicide by vehicle, DUI and related offenses.