The Padres selected Eickhoff's contract from their alternate training site prior to Sunday's game against the Rockies.
He'll assume the active roster spot of first baseman Eric Hosmer (illness), who was placed on the 10-day injured list Saturday with a non-COVID-19-related illness. Though all but three of Eickhoff's previous 78 major-league appearances -- all with the Phillies -- came as a starter, the right-hander is expected to work in a long-relief role for San Diego.