Since English has been an international language, how to enhance English levels of people by useful computer assisted learning forms or tools is a critical issue in non-English speaking countries. Past studies confirmed that reading articles with annotated contents enable knowledge sharing and improve the reading comprehension of learners. However, the self-regulated learning (SRL) ability of individual learners when reading learning materials and contributing annotations becomes a key factor affecting reading performance. Thus, this work proposes a SRL mechanism combined with a digital reading annotation system (DRAS) to enhance Grade 7 students to generate rich and high-quality annotations for promoting English-language reading performance. To evaluate the effectiveness of the proposed system, this work adopts a quasi-experimental design to assess an experimental group and control group learners who respectively use the proposed DRAS with and without the SLR mechanisms when reading English-language texts online. Compared with the control group learners, experimental results demonstrate that the reading comprehension and reading annotation abilities of the experimental group learners were significantly improved. Analytical results also confirm that gender differences in reading comprehension and annotation ability existed when using the proposed DRAS with and without the SRL mechanisms to read English-language texts online. Experimental results also show that significant differences existed in the reading comprehension and annotation abilities of learners with good and poor SRL abilities in the experimental group. Additionally, the reading annotation ability of learners in the experimental group was significantly correlated with reading comprehension.