The available classifications of self-regulated learners may not be applicable to second or foreign language writing due to the contextual nature of self-regulated learning. This study intended to fill the gap by exploring the profiles of English as a foreign language (EFL) learners' writing self-regulation and their association with writing-relevant individual differences. A total of 391 tertiary students from Southwest China were recruited to participate in the current study, including freshmen, sophomores, and juniors. Their writing self-regulation was measured by the Writing Strategies for Self-Regulated Learning Questionnaire. Latent profile analyses discovered two profiles of self-regulated learners in EFL writing: "highly self-regulated group" and "moderately self-regulated group". Moreover, ANOVA and Welch's Test showed that the participants assigned to the two profiles differed significantly in L2 grit, writing achievement goals, and writing self-efficacy rather than language aptitude and working memory. Perseverance of effort, mastery goals, and self-regulatory self-efficacy are found to predict profile membership significantly. Additionally, the results of path analyses revealed that the profiles varied in the predictive effect of individual differences on EFL learners' writing regulation. These findings contributed to furthering our understanding of classification of self-regulated learners and the role of individual differences in the classification.