We report a copper metallaphotocatalytic 1,2-difunctionalization of terminal alkynes with N-hydroxyphthalimide (NHP) esters and readily available silyl reagents (TMSCN and TMSNCS) to access stereodefined trisubstituted alkenes, including (E)-alkenyl nitriles and thiocyanates. The reaction proceeds with excellent anti-stereoselectivity and demonstrates broad compatibility with a wide range of terminal alkynes and NHP esters as alkyl radical precursors. Experimental and computational studies have been performed to gain insight into the reaction mechanism.