Prickly pear (Opuntia ficus indica (L.) Mill.) is a rich source of vitamins C, B1, B2, A, and E, minerals such as calcium, potassium, magnesium, iron, and phosphorus, as well as bioactive substances, i.e., carotenoids, betalains, and phenolic compounds. Of these, the phenolic acids, betalains, and flavonoids are notable in that they are largely responsible for the health-promoting properties of this plant. The purpose of the presented research was to first determine the antioxidant properties and the content of polyphenolic compounds (including individual phenolic acids) in prickly pear fruit, then to produce an innovative gluten-free pasta from rice-field bean flour enriched with various amounts of pear prickly fruit. The content of free phenolic acids, the sum of polyphenols and antioxidant properties of pasta were subsequently determined in the supplemented pasta. Chromatographic analysis (HPLC-ESI-MS/MS) showed a wide variety of phenolic acids. In the fruit sample, 14 acids were detected, whereas in the pasta sample without additives, 9. The dominant acid was isoferulic. The total content of free phenolic acids and the sum of polyphenols increased with increasing content of the functional additive. Moreover, the content of individual acids generally increased as the Opuntia fruit was added. The antioxidant activity was also positively correlated with the addition of fruit, with the content of free phenolic acids and the sum of polyphenols. Our research has shown that our innovative pasta with the addition of prickly fruit can become a source of the free phenolic acids indispensable for human health.