In the past decade, social media has revolutionized communication patterns across the globe, playing a transformative role in language usage and vocabulary development. In Pakistan, a linguistically diverse nation where English functions as both a second language and a marker of social capital, platforms such as Facebook, Twitter (X), Instagram, TikTok, and WhatsApp have become not only communication tools but also agents of lexical innovation. This research explores the influence of social media on English vocabulary acquisition, adaptation, and hybridization among Pakistani youth and young adults. By employing a mixed-methods approach—comprising surveys, content analysis, and semi-structured interviews—the study investigates how social media contributes to the incorporation of neologisms, abbreviation culture, hashtags, emojis as semantic tools, and the phenomenon of code-switching between English, Urdu, and regional languages. The results indicate that frequent social media users develop a distinct digital lexicon that deviates from conventional English norms, marked by informality, technological metaphors, and sociolects. English vocabulary on social media is shaped not only by global trends but also by localized cultural expressions, creating a dynamic linguistic ecosystem. The findings further reveal that while social media enriches vocabulary and enhances expressive range, it also contributes to the erosion of grammatical structures and the rise of linguistic hybridity. This paper argues that English in Pakistan is undergoing a shift, influenced by digital communication, with long-term implications for language teaching, cultural identity, and intergenerational communication. The study contributes to sociolinguistic literature by contextualizing English vocabulary change within a South Asian digital environment and suggests pedagogical strategies for integrating socially relevant vocabulary into formal English education. Recommendations are made for educators, linguists, and policymakers to bridge the gap between formal English instruction and digital language realities.