The Williston Basin retained a high‐resolution record of global δ13C fluctuations during the ~13 Ma duration Upper Ordovician–lower Silurian, and is a possible missing link in correlations between Laurentian margins and its interior. This study integrates δ13C and conodont biostratigraphy to yield a high‐resolution, continuous composite spanning from the Upper Ordovician Aphelognathus grandis Zone into the lower Silurian Distomodus staurognathoides Zone. From oldest to youngest, six global δ13C excursions are identified: (1) Whitewater (=Moe) and (2) Elkhorn (=Paroveja) in the Amorphognathus divergens Zone; (3) LHICE (KaH?) in the Aphelognathus shatzeri Zone; (4) HICE in the Ozarkodina hassi Zone; (5) Early Aeronian within the Distomodus kentuckyensis–Pranognathaus tenuis zones and (6) late Aeronian within the Psuedolonchodina expansa–D. staurognathoides zones. This δ13C record helps to alleviate some of the uncertainties in determining the precise order, duration and timing of events influencing the biotic, climatic, oceanic and sea‐level evolution of the Upper Ordovician–lower Silurian successions across Laurentia.