A blended learning environment is becoming more and more important in all subject areas, especially language education. This study is conducted to investigate the effects of blended EFL writing activities on students' perceptions and writing performance. This study employs both quantitative and qualitative research methods. An experiment (n=40) was conducted with two groups of English majors having the same curriculum, course-book, facilities for 15 weeks. The experimental group takes weekly writing activities online while the control group does not. After the experiment, the experiment group was surveyed (n=20) and interviewed (n=12). Independent samples T-tests show that the experimental group doing their writing activities in a blended environment performs better than the control group doing those activities on paper. The questionnaire and interview data further confirm that students have positive perceptions of EFL writing activities in blended classes. It is suggested that EFL students should be given online writing activities blended with their traditional sessions. Designing interesting writing tasks, providing good topics for discussion, creating a more interactive online environment that boosts collaborative learning are good ways to motivate students and improve student performance.