This correlational type of research aimed to determine the level of mathematics critical thinking skill and language proficiency of prospective secondary Mathematics teachers and the relationship between the two variables. There were two instruments used in this study. The researcher-made instruments administered are a 30-item language proficiency test and a 20-item mathematics critical thinking problems test. To ascertain the validity of the tests, the instruments underwent face-content validation. The researchers gathered data through a test conducted to the senior and junior prospective mathematics teachers of West Visayas State University who are taking up Bachelor of Secondary Education, major in Mathematics. The quantitative data analysis involved were mean, standard deviation, and Pearson’s r. The results show that the prospective secondary mathematics teachers have average mathematics critical thinking with a mean score of 10.00 and standard deviation of 2.26. Also, the secondary mathematics teachers have average language proficiency with a mean score of 18.00 and standard deviation of 2.62. Furthermore, correlation result shows that there is significant positive relationship between mathematics critical thinking skill and language proficiency of prospective secondary mathematics teachers. This implies that mathematics teachers must give emphasis in the development of the mathematics critical thinking skill of the prospective mathematics teachers to equip them in the field of secondary mathematics education. Prospective teachers should also engage themselves in activities that could enhance their critical thinking skill and language proficiency. The curriculum planners may take actions to create opportunities that will enable students to use language to communicate their mathematical ideas. The higher education institutions (HEIs) used to strive to improve the language proficiency of prospective mathematics teachers because it has bearing to their mathematics critical thinking skill.