AbstractCorn (Zea mays L.) silage and alfalfa (Medicago sativa L.) rotations dominate dairy forage production in temperate regions, but low yields during establishment of spring seeded alfalfa limits productivity and profitability. Interseeding alfalfa with corn silage is a novel establishment method that could enhance environmental quality, alfalfa production, and farm income, but it also incurs additional costs. Forage yields derived from long‐term field studies in Wisconsin along with feed values and input costs from 2012 to 2017 were used to predict net returns of corn silage–alfalfa rotation sequences that utilized conventional spring seeding or interseeding for alfalfa establishment and cereal rye (Secale cereal L.) as a winter cover crop following corn silage. Interseeded rotations yielded annual net return of $303 to $367 ha−1, with a 3‐yr corn and 3‐yr alfalfa sequence identified as the most profitable. Conventional rotations provided lower annual net returns of $260 to $320 ha−1 and the most profitable was a 4‐yr corn and 4‐yr alfalfa sequence. Sensitivity analyses demonstrated that interseeded alfalfa had a robust economic benefit, with increased net returns obtained when the corn yield penalty was limited to less than 20% or the success rate of alfalfa establishment exceeded 49% of attempts for the most profitable interseeded rotation sequence. A plant protective chemical application to interseeded alfalfa provided a net economic benefit if it increased the success rate of alfalfa establishment by at least 16%. Interseeding alfalfa into corn silage is predicted to enhance profitability of corn–alfalfa based cropping systems.