In an era where mobile phone use is ubiquitous, being constantly available has become a prevalent norm. Grounded in the sociocognitive model of connectedness (SMC), this study examines the relationship between availability pressure and habitual checking of mobile social media while probing the moderating role of social media notifications in this relationship. Crucially, our study extends the SMC framework by investigating the various impacts of mobile social media modes on availability pressure and the habitual checking of mobile social media. The findings reveal a positive relationship between availability pressure and habitual checking, as well as the role of availability pressure in mediating the effects of voice calls and text messages on habitual checking of mobile social media. The moderated mediation model also reveals that the mediating effect of availability pressure is strengthened by an increase in social media notifications when individuals use voice calls and text messages to interact with friends on mobile social media. This research underscores the complex interplay among mobile social media modes, availability pressure, and social media notifications in shaping habitual media behaviors.