Preparing chiral polymers by using achiral building blocks in an achiral reaction environment is very demanding because this strategy avoids the use of expensive chiral reagents. Here, a surface-confined and sequence-controlled chiral copolymer is synthesized by the organometallic reactions between the achiral precursors 4,4"-dibromo-1,1':3',1''-terphenyl and 1-ethynyl-4-[2-(4-ethynylphenyl)ethynyl]benzene on an achiral Ag(111) surface. Combined scanning tunneling microscopy and density functional theory explorations show that the terminal alkyne and aromatic bromide precursors undergo dehydrogenated and debrominated metalations with surface Ag adatoms to yield the organometallic polymeric products. Despite the achiral precursors and substrate surface employed, the [phenyl-Ag-alkynyl-Ag-phenyl-Ag]