The use of 3D printing in science, technology, engineering and mathematics (STEM) learning is a promising way for integrated STEM education. This study examined the influence of 3D printing infused STEM integration on students' interest in STEM careers, which is essential for students to participate in STEM disciplines and future STEM careers. The participants included 26 teachers across six states in the United States and their 1455 students in primary and secondary classrooms. Teachers' lesson plans were analysed to examine the level of 3D printing and STEM integration. Students' interest in STEM careers was measured using a previously validated career interest scale. Cluster analysis and multiple regression analysis indicated that girls were more interested in empathetic STEM careers, whereas boys were more interested in analytic STEM careers. While 3D printing integration level was not a significant predictor, teachers' STEM integration level positively predicted students' interest in both analytic and empathetic STEM careers.