Classrooms today are no longer homogeneous spaces of one‐size‐fits‐all learners. Diversity in learning styles, cognitive abilities and modes of expression demands assessment practices that are flexible, inclusive and responsive. Though classroom assessment continues to remain largely rote-driven and product-oriented, Universal Design for Learning (UDL) offers a student-centric framework. This study investigates the effectiveness of sketchnoting as a formative assessment strategy. The research was conducted on a sample of 200 B.Ed. student teachers from a teacher training college in Mumbai, selected using the repeated cross-sectional sampling technique. The CAP Learning scale was used to document development across the cognitive, affective and psychomotor domains. The repeated measures MANOVA established the overall effectiveness of sketchnoting, revealing a significant multivariate improvement in cognitive, affective and psychomotor development, thereby validating its role as a holistic formative assessment tool within UDL classrooms. Findings revealed that sketchnoting promoted creativity, learner engagement and higher-order thinking. It emerged as a powerful strategy for making thinking visible, enabling learners to organise ideas visually, integrate concepts meaningfully and communicate understanding, enhancing the development of 21st century skill sets such as critical thinking, creativity, and communication. Most importantly, it fostered positive attitudes and psychomotor engagement catering to the needs of kinaesthetic learners. The results underscore the pressing need for a paradigm shift from memory-based evaluation to inclusive formative assessment aligned with UDL principles. The study concluded that sketchnoting not only caters to diverse learning styles but holistically nurtures the three domains of learning, offering vital educational implications for transforming assessment practices in 21st century classrooms.