A "click and activate" strategy was designed and executed in a four-component, stepwise condensation that led to a trisubstituted triazolyl-pyridazinone library. This one-pot process included regioselective azide substitution at 2-substituted-4,5-dichloropyridazinones, followed by a Cu(I) catalyzed triazole formation which triggered subsequent nucleophilic substitution at the neighboring position to achieve three points of diversity.