Objective: The objective of the study was to assess the efficacy of the use of cyanoacrylate glue (CAG) as a means of securing midline catheters and peripherally inserted central catheters with the modified micro-Seldinger technique in adult hospitalised patients. Methods: Randomised clinical trial with two groups (1:1): control and intervention. The control group received a securement method with a sutureless device plus transparent dressing and the intervention group received the same securement method plus the CAG. The study was approved by the Drug Research Ethics Committee of the Lleida Health Region. Results: A total of 216 patients were assessed. The two groups of the trial were homogenously distributed in terms of sociodemographic and clinical variables. The intervention group had a statistically significant lower incidence of peri-catheter bleeding and/or oozing during the 7-day study period (odds ratio (OR), 0.6; 95% confidence level (CI), 0.44–0.81; p < 0.001) and a statistically significant lower incidence of catheter dislodgements during the first 24 h (OR, 0.2; 95% CI, 0.04–0.91; p = 0.03). There were no statistically significant differences in the incidence of phlebitis (OR, 1.30; 95% CI, 0.60–2.83; p = 0.56) or catheter-related pain (OR, 0.88; 95% CI, 0.40–1.94; p = 0.84). Conclusion: Midline catheters and peripherally inserted central catheters secured with CAG had fewer complications than catheters not secured with this adhesive.