This study investigated the effect of peer assessment in Oral English achievement of senior secondary school students in Bayelsa State and the moderating influence of learning style. The study used the quasi-experiment research design. The population for this study consisted 24,769 senior secondary school II students in Bayelsa state. The sample for this study consisted of 360 senior secondary school students in class 2 (SS2) of public secondary schools in Bayelsa State, Nigeria. Two instruments were used for the study. They were the ‘Oral English Achievement Test (OEAT)’ and the VARK Questionnaire. “The Oral English Achievement Test (OEAT) contained 25 standardized multiple choice items and was marked over 100. On the other hand, the VARK scale was a multivariate instrument with four subsections that measured the student’s method of learning. It was composed of 32 items with 8 items in each sub-sections. Face and content validity of the instrument was determined by giving it to three experts in Measurement and Evaluation specialty in the Department of Educational Psychology, Guidance and Counselling in University of Port Harcourt. Reliability of the instrument was determined using KR20. After analysis, a reliability coefficient of 0.79 was realized indicating that the instrument was highly reliable. On the other hand, the reliability of VARK was established using Cronbach Alpha method of reliability with an index of 0.80. Mean, standard deviation, and, paired sample t-test and ANCOVA were used to analyze the data. Findings revealed that there is a significant difference in achievement of students in peer-assessment group (p=0.001<0.05). Based on these finding, it was recommended among others that student should be encouraged by the classroom teacher to carry out peer-assessment from time to time since it has been seen that it improves the achievement of student especially in oral English.