Researchers have conducted numerous studies on the positive effects of intrinsic motivation to learn mathematics and the negative impact of mathematics anxiety on students' performance in mathematics literacy. The study examined how the introduction of cognitive activation in mathematics lessons, a mediator variable, would alter these effects between the independent and dependent variables. We used structural equation modeling to analyze data. This study examined data from 2012 for 4500 Australian students. Participants were between 15 and 16 years old. The first model analyzed the entire data set, the second model considered gender, and the third model focused on students' socioeconomic status. The whole sample showed a positive correlation between intrinsic motivation to learn mathematics, cognitive activation, and performance in mathematics literacy, irrespective of gender and students' socioeconomic status. The whole sample showed a negative correlation between mathematics anxiety, cognitive activation, and performance in mathematics literacy. For the whole sample, the independent variables (mathematics anxiety and intrinsic motivation) partially mediate the cognitive activation in mathematics lessons.