The cultivation and commercialization of American elderberries (Sambucus nigra subsp. canadensis), rich in acylated anthocyanins, is nascent. In this study, American elderberry juice and pomace extract were spray dried using soy protein isolate (SPI) or tapioca starch (TS) as carriers to develop functional food ingredients. Physicochemical, morphological, and bioactive properties were analyzed, and an in vitro gastrointestinal digestion model was used to study polyphenol bioaccessibility. An efficient spray drying process (solids recovery >60%) was established. Elderberry particles produced with SPI had higher solubility (60%–64%), lower porosity (69%–70%), and better flowability (22% Carr index, 1.29 Hausner ratio). Spray dried particles produced with tapioca starch showed significantly higher total polyphenol content (42–49 mg gallic acid equivalent/g sample), proanthocyanidin content (0.76–2.86 mg proanthocyanidin-B2/g sample), and anthocyanins (7.86–33.80 mg/g sample) for both elderberry juice and pomace extract, compared to SPI-derived ones. Particles of encapsulated elderberry juice or pomace extract with SPI had higher bioaccessibility compared to non-encapsulated elderberry juice or TS-derived particles. Overall, spray drying American elderberry juice and pomace extract is an effective and sustainable strategy to create novel ingredients for multiple food applications. These findings offer an industry-friendly technological solution to develop value-added ingredients for the emerging American elderberry market.