It is now undeniable that young people and the Internet has become inseparable. Nonetheless, the uncontrolled use of it causes many problems among young adults including academic procrastination. Previous studies stated that academic procrastination lead to low of academic achievement. The reason of why young adults use the internet excessively and got negative outcomes in academic life did not stated clearly. The objective of this study was to find out the empirical evidence of PIU as a mediator between loneliness and academic procrastination. Sample consisted of 320 undergraduate students from 10 universities. Age range was 17-25 years old (M=20.17, SD=1.49). They were given three self-report questionnaires such as GPIUS2, SELSA, and TPS. Those instruments were adapted in Indonesian language. Data were analyzed with Structural Equation Modelling (SEM). The results showed that the model was good fit (χ2=416.541, df=205, p<0.001, CFI=0.902, TLI=0.879, SRMR=0.068, RMSEA=0.057, 90% CI:0.049-0.065, p good to fit 0.05). This study give contribution on loneliness, PIU, and academic procrastination as one model. It also gives implication of social media using among young people and policy making in universities about students life.