Cranberry pomace is a rich, but underutilized source of polyphenols and other bioactive compounds. This study assessed the efficacy of six solvent mixtures comprising combinations of ethanol, methanol, acetone, formic acid, and water for extraction of antioxidants from pomace. The antioxidant activity and total phenolic content of the cranberry pomace extracts were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS•⁺(2,2′-azinobis(3-ethylbenzthiazolin-6-sulfonic acid), FRAP (ferric reducing power), and Folin–Ciocâlteu assays, the total proanthocyanidin content was estimated using the dimethylaminocinnamaldehyde (DMAC) method, and individual polyphenolics and triterpenoids were determined using HPLC-DAD and UPLC-MS. Extracts exhibited a broad range of total phenolic content at 21–166 mg gallic acid equivalents (GAE)/g extract), total PACs (proanthocyanidins) at 6–240 mg PAC equivalents/g extract, anthocyanins at 0.42–1.77 mg/g extract, flavonols at 4.09–11.7 mg/g extract, and triterpenoids at 85.6–287 mg/g extract. Antioxidant activities varied widely and correlated positively with all polyphenol categories, but negatively with triterpenoids. An extract produced using an acetone, methanol, water and formic acid mixture demonstrated optimal antioxidant properties, total phenolic content, and total proanthocyanidin content and was further characterized. Our findings emphasize the importance of solvent selection for targeted bioactive constituents and highlight cranberry pomace as a promising source of antioxidants.