Background: Socioeconomic status (SES) is important in students' reading development. The mechanism of how they are linked, however, is underexplored.

Aims This research aimed to explore whether reading self‐concept mediates the link between SES and reading achievement and whether teacher support moderates the direct and indirect link between SES and reading achievement.

Samples: Using PISA 2018 database, we selected 17,346 15‐year‐olds from 537 schools in B‐S‐J‐Z (China) and the United States (U.S.).

Methods: Multilevel linear models were calculated to explore the potential mediation of self‐concept and the potential moderation of teacher support between SES and reading achievement.

Results: Results reveal that reading self‐concept mediated the link between SES and reading achievement at student level both in China and the United States, and teacher support moderated the link between SES and reading self‐concept both at student level and school level only in China, but not in the United States.

Conclusion Our research highlights the importance of self‐concept and teacher support in improving students' reading achievement, especially for students of low SES, which has important theoretical significance and practical enlightenment for reading instruction. (PsycInfo Database Record (c) 2023 APA, all rights reserved)