Given the wide-ranging influence of the internet on people in this digital age and the extensive reliance of young people on internet-enabled mobile devices, our study aimed to assess the pattern of online health information seeking behavior among undergraduate students in a Nigerian private university. Employing the cross-sectional survey design and purposive sampling technique, three hundred and four (304) undergraduates took part in the study. A semi-structured questionnaire was used to collect information on the socio-demographic characteristics, participant’s use of the internet, online health information seeking behaviour and use of online health information. The results showed that the mean age of 20.012.34 years whereby the age range of the respondents was from 15 to 29 years. Also, most of the students were active users of the internet as 94.1% used the internet daily while 83.2% used the internet for health purpose. Topmost among the reasons given for usage and non-usage of the internet for health information included convenience (74.3%) and unreliability (10.5%) respectively. Majorly (67.1%) of the respondents sought online health information using the Google search engine. Skin conditions (62.5%) and sexual/reproductive health (59.9%) were the most searched topics. Also, most (51%) used online health information as a basis for lifestyle change while only 38% consulted health professionals after obtaining online information. In conclusion, the internet has assumed a very important role in the lives of undergraduate students in Nigeria, more so in the area of seeking for health information. There is therefore an urgent need to promote information literacy tailored towards online health information among undergraduate students in particular and young people in general. There is a need for practitioners in the Nigerian health sector to take an active position in regulating and ensuring the availability of health-related information, especially that which is related to locally common health conditions.