Coastal highway bridges, particularly those with reinforced concrete members, are susceptible to chloride-induced corrosion in their lifetime due to the aggressive coastal environment. Such an adverse environment has also witnessed the susceptibility and vulnerability of bridges to multi-hazard events during their service life; such events include but are not limited to scour and earthquake-induced liquefaction. This study carries out a risk-informed assessment to understand the influence of corrosion (represented by service time) and scour (represented by scour depth) on the seismic behavior of coastal bridges in liquefiable ground. To this end, a typical highway bridge is adopted as a testbed structure, which is simulated using OpenSees with a multi-dimensional soil-structure modeling technique. Through probabilistic seismic demand analyses and capacity modeling, fragility curves are generated for different scenarios of corrosion, scour, and liquefaction effects. Together with probabilistic seismic hazard analyses, time-dependent seismic risk of highway bridges can be obtained to better understand the roles of these effects in the lifetime performance assessment. It is found that the seismic risk of bridge pile foundation apparently increases with the increase of service time as well as scour depth. In particular, the role of scour depth becomes significant during service time from 40 to 60 years. This pilot study can facilitate risk-informed decisions on the life-cycle management of coastal highway bridges under the ever-changing multi-hazard threats.