In a fast-changing and hyper-connected business environment, startups are increasingly challenged to innovate, scale efficiently, and remain competitive despite limited internal resources. This paper investigates how digitalisation and open innovation (OI) jointly impact the performance of innovative startups, with a particular focus on how digital technologies enable open innovation processes. To address this, the study adopts a systematic literature review (SLR) methodology, analysing 42 peer-reviewed articles retrieved from the Scopus database. The selected studies span various industries and geographic regions, although the majority are concentrated in developed economies and ICT-intensive sectors. The review identifies a growing interest in the role of technologies such as Artificial Intelligence (AI), Big Data Analytics (BDA), Internet of Things (IoT), Blockchain, and Cloud Computing as key enablers of both inbound (e.g., external knowledge sourcing) and outbound (e.g., licensing, platform participation) open innovation activities. Findings show that while digitalisation and OI are often studied in isolation, few models offer an integrated, startup-specific perspective. Moreover, most existing frameworks focus on financial performance, neglecting sustainable performance metrics such as environmental and social value creation. The analysis highlights several theoretical gaps, including a lack of longitudinal and cross-sectoral studies, and limited exploration of digital open innovation dynamics in early-stage firms. From a theoretical standpoint, the study maps the most frequently adopted frameworks—Resource-Based View (RBV), Dynamic Capabilities Theory (DCT), Knowledge-Based View (KBV), and Open Innovation theory—and proposes a conceptual model linking digital technology adoption, open innovation practices, and dual performance outcomes (financial and sustainable). This model provides a foundation for future empirical testing and theoretical refinement. On the managerial side, the paper offers practical insights for startup founders, innovation managers, and ecosystem developers, suggesting how digital tools can be strategically combined with open innovation practices to enhance agility, reduce costs, and drive long-term value creation. Overall, this study contributes to the literature by clarifying conceptual relationships, identifying key constructs, and outlining directions for future research at the intersection of digital transformation and collaborative innovation in startups.