Accumulating evidence suggests that diets rich in (poly)phenols may have positive effects on human health. Currently there is limited information regarding the effects of processing on the (poly)phenolic content of berries, in particular in processes related to the baking industry. This study investigated the impact of cooking, proving, and baking on the anthocyanin, procyanidin, flavonol, and phenolic acid contents of wild blueberry using HPLC with UV and fluorescence detection. Anthocyanin levels decreased during cooking, proving, and baking, whereas no significant changes were observed for total procyanidins. However, lower molecular weight procyanidins increased and high molecular weight oligomers decreased during the process. Quercetin and ferulic and caffeic acid levels remained constant, whereas increases were found for chlorogenic acid. Due to their possible health benefits, a better understanding of the impact of processing is important to maximize the retention of these phytochemicals in berry-containing products.