Over time, there has been the alternative metrics complementing the traditional citation counts in scientometrics. The awareness, knowledge and use of these altmetrics tools in measuring research impact are unknown among Nigerian librarians. Hence, this study examined the awareness, knowledge and use of altmetrics as measure of research impact by Nigerian librarians. Descriptive survey research design was adopted for the study and total population sampling technique was adopted. Web-based questionnaire was used to collect data for the study. Two hundred and eighty-five responses were collected from the participants. The findings of the study show that most Nigerian librarians were not aware of altmetrics as non-traditional complement to traditional citation count. Results show that Nigerian librarians did not use altmetrics for measuring their research impact. It was shown that there was inadequate knowledge of altmetrics and it was unpopular among Nigerian librarians in measuring research impact. It was found that there was no statistically positive significant (r = .482**; P < .022) relationship between awareness and use of altmetrics to measure research impact by Nigerian librarians. Results show that there was no statistically positive significant (r = .374**; P < .039) relationship between librarians’ knowledge and use of altmetrics to measure research impact. It was concluded that that most Nigerian librarians use Twitter to seek altmetrics compared to other social media networks such as Facebook and LinkedIn which have very minimal usage.