The study investigated loneliness and social media as a correlate of psychological well-being among undergraduate students, One hundred and sixty-eight (168) undergraduate students with a mean age of 20.66 and S.D of 1.125 were drawn using multi-stage (cluster, simple random: by balloting and purposive) sampling techniques as participants from Enugu State University of Science and Technology, Enugu. Psychological Well-Being Scale, UCLA Loneliness Scale and Bergen social media addiction scale were used for data collection, a correlational design was adopted, while a PEARSON moment coefficient with the aid of SPSS version 27 was used for data analysis. Findings revealed that Loneliness positively relates to autonomy r= .434* at p< .05 and negatively relates to personal growth r= -.427* at p< .05. Social media addiction positively relates to Environmental self-mastery r= .378*, purpose in life r= .355* at p< .05 and positive relations with others r= .489** at p< .01 dimensions of psychological well-being, Hence school authorities should try and bring up coursework that can help students to channel a positive energy towards social media, so that they can use it to their advantage