The contemporary Nigerian retail landscape is characterized by intense competition and increasing consumer sophistication, yet persistent lapses in customer service quality (CSQ) remain a critical barrier to sustainable competitive advantage and customer retention. This study aimed to empirically evaluate the role and differential impact of various employee training types on perceived CSQ, measured through the customer's perspective, in Nigerian retail organizations. Utilizing a quantitative, cross-sectional survey design, data were collected from 412 customers and 145 frontline employees across major retail chains in Lagos and Abuja. CSQ was measured using a modified SERVQUAL instrument, while training effectiveness data were gathered from employee self-assessment and HR records, categorized into Product Knowledge, Soft Skills, and Service Recovery training. Multiple regression analysis revealed that both Soft Skills Training (β=0.45, p<0.001) and Service Recovery Training (β=0.31, p<0.01) were significant positive predictors of overall perceived CSQ. Specifically, soft-skill training exhibited a strong correlation with the Empathy and Responsiveness dimensions of service quality, which were also identified as the largest negative service gap areas. Conversely, a one-time product knowledge training showed a weak, non-significant link to overall CSQ. The findings underscore that a strategic, continuous investment in interpersonal and problem-solving skills is crucial to bridging the service delivery gap in the Nigerian context. The study concludes that training is a high-leverage investment that transforms employees from transactional clerks into empowered service agents, recommending a shift from basic product orientation to scenario-based training for sustainable retail excellence in Nigeria.