Nurses often administer intramuscular (IM) injections. However, they do not use the ventrogluteal (VG) site, although it is highly recommended. This study investigated whether a mobile-assisted training and counseling program (intervention) encouraged nurses to use the VG site to administer IM injections. This study adopted a pretest-posttest interventional design with no control group and employed a mixed research design. The sample consisted of 105 nurses from a public hospital in a metropolitan city in Turkey. Quantitative data were collected using a descriptive characteristics form and a Ventrogluteal Site Information Form (VSIF). Qualitative data were collected using a semi-structured interview form. First, participants took a pretest and then watched an animation about VG injections on their mobile devices. Afterward, they were provided with counseling and then administered a posttest. Sixteen participants were interviewed after the posttest. Participants had a significantly higher mean posttest VSIF score (17.50 + 3.23) than the pretest score (12.73 + 5.40) (p < 0.05). They stated that the intervention helped them reinforce what they already knew and encouraged them to use the VG site to administer IM injections. They also noted that it boosted their confidence and helped them experience less anxiety. The results showed that the intervention helped participants learn more about IM injections into the VG site. Therefore, hospitals should provide nurses with mobile-assisted training and counseling programs to encourage them to use the VG site to administer IM injections.