The present study aimed to examine the relations of early numeracy activities and skills to mathematics dispositions, engagement, and achievement among 26,859 fourth graders in the United Arab Emirates who took part in the sixth cycle of the Trends in International Mathematics and Science Study (TIMSS) in 2015. The study also explored the mediating effects of mathematics dispositions and engagement on the relations between early numeracy activities and skills and mathematics achievement among these fourth graders. Results of path analyses, after controlling for participants’ demographic and socioeconomic characteristics, indicated that early numeracy activities and skills were significantly and positively related to mathematics dispositions, engagement, and achievement. Further, results of mediational analyses suggested that confidence in mathematics had a significant mediating effect on the relations between early numeracy activities and skills and mathematics achievement. The findings of the study highlight the crucial role that early numeracy activities and skills play in enhancing fourth graders’ mathematics dispositions, engagement, and achievement in the United Arab Emirates.