The current quasi-experimental research aimed at exploring the influence of Lexically-Based Language Teaching (LBLT) on task response and coherence and cohesion aspects of the writing proficiency of Iranian university EFL learners. The research sample of the study included sixty male and female university students (N = 60) attending two university classes. They were selected by using a convenient sampling procedure and were assigned to experimental and control groups. To ascertain the groups' homogeneity at the beginning of the study, the researchers gave two groups the Key English Test (KET). Prior to starting treatment, two groups took the pretest writing task. While the participants comprising the experimental group were instructed consistent with the lexical approach's underlying practices and activities, those constituting the control group were instructed based on conventional techniques applied to present essay writing in universities. At the end of the experiment, the posttest writing, identical to the pretest, was given to both groups. To compare the two groups' mean scores with respect to coherence and cohesion and task response aspects of post-test writing, One-way Analysis of Covariance (ANCOVA) and independent T-test were drawn upon. Version 20th of the SPSS software was applied for this end. The attained results were indicative of a significantly positive influence of the lexically-based language teaching on both coherence and cohesion and task response aspects of writing proficiency. However, the attained improvement was greater in the task response aspect. The findings suggest some implications for English language teachers and university instructors.