<p>This study aimed, first to assess the chemical composition of date (<i>Phoenix dactylifera</i> L.) syrup and powder, which had been obtained using environmentally friendly processes, in terms of ash, moisture, sugars, proteins, fats and Hydroxymethylfurfural. In addition, the antioxidant and antidiabetic activities were evaluated. Second, to investigate the impact of different mixture concentrations (powder in syrup) on the physicochemical, technological, microbiological and sensorial qualities of probiotic bilayer yogurt during 28 days of refrigerated storage. Both, date syrup and powder found a significant difference in chemical composition. In fact, date powder presented the high antioxidant (5823.22 ± 6.33 µmol of Trolox equivalent/g) and antidiabetic activities (82.62 ± 2.04%) compared to date syrup. Both ingredients enhanced the growth and stability of the yogurt starter culture, thereby improving the probiotic potential of <i>L.rhamnosus</i> LGG in date-added bilayer yogurts with the number of 7.85 log CFU/mL at the end of storage. Physicochemically, the addition of date powder in syrup at 17, 27 and 37% induced significant modifications in pH (4.15 ± 0.02), acidity (0.58 ± 0.02%), color and syneresis (57 ± 0.0%) in probiotic yogurt with 37% of powder in syrup date (PBY37%). During storage, date coproducts hence maintained yogurts’ rheological quality. For sensorial analysis, consumers preferred the yogurts with date powder in syrup bilayer because its addition led to functional food and more brownish color and granular texture thereby enhancing consumer’s acceptability of the product. In this sense, both date syrup and powder proved to be valuable by-products developed to combat food waste.</p> Graphical Abstract <p></p>