Teacher evaluation policies have been central to policy efforts to enhance teaching quality. At the same time, ambitious mathematics instruction has been emphasized by teacher education programs as well as by the Common Core State Standards. Drawing on observation and survey data from early-career teachers, this study examines how teachers' perceived pressure of teacher evaluation policies shape their ambitious mathematics instruction. We found that teachers who perceived a strong pressure of teacher evaluation on their instructional practices tended to move further away from enacting ambitious mathematics instruction. Moreover, the negative association between the pressure of teacher evaluation and ambitious instruction was stronger for teachers with a high level of mathematical knowledge for teaching.