This study aimed to explore the predictive value of self-regulation, critical thinking, and creative thinking on the writing performance of Iraqi EFL learners on TOEFL iBT, including both integrated and independent writing tasks. To this end, 300 advanced male and female Iraqi EFL learners took the Cornell Critical-Thinking Test-Level X, the Alternate Uses Test, and the writing section of TOEFL iBT and filled out the Self-Regulation Questionnaire, resulting in a total of five scores per participant. Three separate multiple regression analyses were conducted to explore the impact of these predictor variables on the integrated, independent, and total writing scores. The findings indicated that all three variables had predictive value in the total and the integrated score, while self-regulation did not impact the writing scores of the independent task. Although critical thinking demonstrated consistent predictive power across all three writing scores, the differentiation in the strength of correlations compared to the other variables highlights their unique contributions to writing performance. The strength of associations varied across the types of writing tasks, suggesting that the nature of the writing task determines the extent of impact each factor might have on learners' performance. Moreover, excessive regulation may hinder the process of freely expressing one's ideas in written format, while creativity may have less impact on summarizing main text ideas. Contemplating such findings may provide valuable insights for the design of writing materials and the instruction of learners especially those preparing for highly standardized English tests.