The scaling of Option B+ services, whereby all pregnant women who test HIV positive are started on lifelong antiretroviral therapy upon diagnosis regardless of CD4 T-cell count, is ongoing in many high HIV burden, low-resource countries. We developed and evaluated a tablet-based mobile learning (mLearning) training approach to build Option B+ competencies in frontline nurses in central Mozambique. Its acceptability and impact on clinical skills were assessed in maternal child health nurses and managers at 20 intervention and 10 control clinics. Results show that skill and knowledge of nurses at intervention clinics improved threefold compared with control clinics (p = .04), nurse managers at intervention clinics demonstrated a 9- to 10-fold improvement, and nurses reported strong acceptance of this approach. "mLearning" is one viable modality to enhance nurses' clinical competencies in areas with limited health workforce and training budgets. This study's findings may guide future scaling and investments in commercially viable mLearning solutions.