Word reading fluency is crucial for early L2 development. Moreover, the practice of digital reading has become increasingly common for both children and adults. Therefore, the current study investigated factors that explain digital word reading fluency in English (L2) among Chinese children from Hong Kong. Eighty-six children (age: M = 9.78, SD = 1.42) participated in a digital silent word reading test using a mobile phone, a computer, or a tablet. This is a 10-minute timed test of English word reading. Overall, children's digital word reading fluency was highly correlated with print word reading fluency, even when measured a year apart. A hierarchical regression model revealed that socio-economic status ([beta] = 0.333), grade ([beta] = 0.455), and English reading motivation ([beta] = 0.375) were positively and uniquely associated with performance in digital reading. These predictors explained 48.6% of the total variance in task performance. Two additional variables, i.e., the type of reading device and extraneous cognitive load, were included as well. Digital word reading fluency was significantly poorer when done using a phone as compared to a computer ([beta] = -0.187). No significant difference was found between reading on a tablet and a computer. Extraneous cognitive load ([beta] = -0.255) negatively and uniquely explained digital word reading fluency as well. Overall, the model explained 58.8% of the total variance. The present study represents the first attempt to highlight a comprehensive set of predictors of digital word reading fluency.