Spatial visualization skills are essential for success in STEM fields, yet many first-year engineering students struggle to develop proficiency in these critical abilities. This study investigates the impact of an innovative online freehand sketching and spatial visualization tool, Spatial Vis™, on students’ spatial reasoning and cognitive skills in a first-year engineering design course. Using a mixed-methods approach, the research examines the effects of the tool through pre-and post-assessments, surveys, and qualitative interviews. The study addresses three key research questions: (1) How does the tool influence students’ spatial visualization skills over the semester? (2) How does sketching with the tool enhance cognitive abilities related to spatial thinking? (3) What are students’ perceptions of the tool’s effectiveness in learning sketching and spatial skills? The findings reveal significant improvements in spatial reasoning, confidence, and engagement among students who used the tool, compared to a control group relying on traditional instruction. This paper discusses integrating the tool into the curriculum, its potential to foster deeper spatial understanding, and its role in bridging the gap between theoretical learning and practical applications in engineering education. By highlighting both quantitative outcomes and student experiences, the study provides actionable insights into designing and implementing digital tools to support learning in STEM disciplines.