The research aimed to examine the effects of teaching professional training in Malaysian Chinese Private High Schools (CPHSs) on mathematics teachers’ pedagogical content knowledge (PCK). A total of 28 respondents were involved in interviews using a multistage sampling technique. The respondents were comprised of four groups, namely five principals, five deputy principals, five mathematics division leaders, and 13 mathematics teachers of the five CPHSs. Principals, deputy principals, and mathematics division leaders participated in in-depth interviews while mathematics teachers involved in focus group interviews. Results revealed that most of the mathematics teachers are possessing PCK excellently except the new teachers. The entire respondents came to an agreement that the teaching professional training is eligible to improve mathematics teachers’ PCK abilities to deal with the varying requests to keep well-informed of the current eras.