This paper reports on a semi-automated microrobotic system for adherent cell injection. Different from embryos/oocytes that have a spherical shape and regular morphology, adherent cells are flat with a thickness of a few micrometers and are highly irregular in morphology. Based on computer vision microscopy and motion control, the system coordinately controls a three-degrees-of-freedom microrobot and a precision XY stage, demonstrating an injection speed of 25 endothelial cells per minute with a survival rate of 95.7% and a success rate of 82.4% (n=1012). The system has a high degree of performance consistency. It is operator skill independent and immune from human fatigue, only requiring a human operator to select injection destinations through computer mouse clicking as the only operator intervention. The microrobotic system makes the injection of a large number of adherent cells practical for testing cellular responses to foreign molecules.