Background: The accelerated aging of the world’s population will lead to an increase in the number of older people in the workforce. Computerized Cognitive Training (CCT) is effective in improving cognitive outcomes, but its benefits for older workers remain controversial. We investigate the real-world efficacy of CCT in the workplace, focusing on employees aged 50+ years from a public sector agency. Methods: Case managers (n = 82) were randomized to either an intervention group (24 40 min CCT sessions two times per week) or a waiting list passive control group. Cognitive ability, well-being, job satisfaction, and productivity outcome measures were collected and assessed before and after CCT or the comparable control wait time. Results: Participants undergoing CCT improved on a task of executive functioning (p = 0.04). There was a trend toward a change in work productivity after CCT (p = 0.09), with the control group showing a significant decrease (p = 0.02), while the intervention group remained stable. Conclusions: CCT during office hours has a positive effect on cognition and well-being without affecting productivity among white-collar office workers. CCT could be considered as an intervention to support the older workforce in managing the cognitive and behavioral challenges of changing workplace demands.