Introduction: High academic achievement in English is a valued key for high school students in Sudan to guide them toward a better life, career, and social opportunities. At the same time, many of the Sudanese students have linguistic, cultural, and rhetorical problems in the English language, and many of them face challenges in expressing themselves in English. Thus, the core purpose of this study is to explore what may help them in this matter; this includes examining the direct effects of the entity and incremental beliefs of intelligence on academic achievement in English and testing the indirect effects through goal orientation. Method: A quantitative research method was used by applying scales of implicit beliefs of intelligence (Dweck, 2000) and goal orientation (Elliot & Church, 1997). The data were collected using a cluster sampling technique from 392 respondents, mainly high school students in Sudan. A structural equation model (SEM-AMOS) of relations among constructs was employed to examine the relationships among the construct variables. Results: The findings of the structural equation modelling indicated that there was no direct effect of entity belief of intelligence and that there was a direct effect of incremental belief of intelligence on academic achievement in English. Regarding the mediation role of the goal orientation in the relationship between entity belief of intelligence and academic achievement in English, there was no mediation role play. Nevertheless, the goal orientation partially mediated the relationship between the incremental belief of intelligence and academic achievement in English among Sudanese high school students. Discussion and Conclusion: Academic achievement in English is influenced by students' motivations, beliefs of intelligence, and goal orientations. Accordingly, the English language of Sudanese high school students requires more attention and consideration for the incremental belief of intelligence, goal orientation, and other significant variables in order to support those students in Sudanese high schools to overcome their weaknesses in English and improve themselves so that they can achieve high scores academically in English.