The research reveals the advantages of using an e-textbook in autonomous learning of the discipline “Foreign Language for Professional Communication (English)” by pre-service teachers of mathematics. The article presents the method of application of the ESP (English for specific purposes) e-textbook “Mathematics”, its structure, and functions. The ESP e-textbook includes learning material of three different levels of language proficiency. Each part contains professional vocabulary and speech situations aimed at forming the necessary skills and abilities in the mathematical field. The authors describe the stages of work with the learning material within a unit of the ESP e-textbook. The necessity of introduction of ESP e-textbooks in the process of learning a foreign language by pre-service teachers of mathematics is justified. The benefits of using the ESP e-textbook by students for autonomous learning are elucidated, and new opportunities for an ESP teacher to structure foreign language classes are outlined in the research. Experimental training with the use of the ESP e-textbook is conducted among pre-service teachers of mathematics at Vinnytsia Mykhailo Kotsiubynskyi State Pedagogical University (Ukraine), where the ESP e-textbook is considered as an element of the learning environment for professional creative activity and accumulation of knowledge in the conditions of autonomous learning. The study presents and analyzes the results of students’ English proficiency tests, and the survey on the students’ attitude to the use of ESP e-textbooks in the process of autonomous learning of ESP. The analysis of students’ surveys shows the effectiveness and expediency of using the e-textbook by pre-service teachers of mathematics in autonomous learning of English for professional communication. In the paper, some samples of educational activities from the ESP e-textbook “Mathematics” are presented.