This study discusses the concepts of “the fear of missing out at work (W-FoMO)” and “smartphone use after work (SUW),” which shed light on the dark side of technology. The study attempts to determine whether W-FoMO affects psychological well-being (PWB) through SUW and “work-family conflict (WFC).” Hypotheses regarding the direct effects as well as the simple-mediation and serial-mediation roles were created with reference to the Conservation of Resources Theory (COR). Data were obtained from 287 female employees working in different sectors in Turkey. The analyses were carried out using the SPSS, AMOS, and Process MACRO software. The findings revealed that W-FoMO has a positive effect on PWB through SUW. The findings also indicate that W-FoMO has a negative indirect effect on PWB through WFC. Moreover, SUW and WFC had a serial mediation role in W-FoMO’s effect on PWB. Therefore, keeping smartphone use after work (SUW) at a reasonable level for female employees with W-FoMO may increase their well-being (PWB), but smartphone use after work at a level that would lead to WFC may decrease PWB. The study discusses the findings and makes theoretical/practical inferences about W-FoMO and its outcomes.