Purpose: This quasi-experimental study examined the effectiveness of audio-visual and written feedback (AVF + WF) on undergraduate students versus only receiving WF in the context of an English as a Foreign Language (EFL) online classroom during the coronavirus disease 2019 (COVID-19) lockdown. Design/Methodology/Approach: The study used the estimator Difference in Difference (DID) to compare a treated and control group in a pre-and post-test under the application of six treatment sessions, plus a student's perception survey at the end of the treatment. The treated group that received the multimodal feedback showed higher improvement rates in the paragraph content between the first and final drafts than students in the control group. Findings: Results indicated that receiving a combination of AVF + WF had a statistically significant effect on mechanics (p < 0.001) and the use of transition words (p = 0.003). Practical Implications: These findings will benefit educational agents, professors and stakeholders for social and economic development. Originality/Value: While previous studies have only used student perceptions of the feedback, this study contributes with empirical data through quasi-experimental analysis and measures the effectiveness of feedback in online learning environments.