Highly regioselective allylation of activated alkenes achieved via visible-light mediated metal-free photoredox-catalysis. The reaction involves in situ generated allylic radicals from allylsilanes via photoinduced single electron transfer (SET) mechanism, which subsequently adds regioselectively to the activated alkenes. The reaction works at ambient temperature in metal-free condition, with no extra additives, tolerates various functional groups and present wider substrate scope. The reaction is also feasible on a gram scale. Allylated products serve as a useful reactive set that can undergo a various synthetic transformation.