This study explored large-scale land acquisition, livelihood diversity, and socioeconomic vulnerability among smallholder farmers in Southeast Nigeria. It assessed the nature and extent of land acquisition, examined the socioeconomic characteristics of affected farmers, identified key livelihood strategies, and analyzed the impact of land acquisition on their livelihoods. Data was gathered from 400 smallholder farmers, utilizing descriptive statistics for analysis. The results revealed that commercial agriculture and plantations were primary forms of large-scale land acquisition, significantly affecting farmers’ access to land, with many experiencing substantial farmland loss. Most respondents were middle-aged, married, experienced farmers, operating small holdings and largely depending on agriculture. While human and social assets were relatively strong, financial assets, especially access to formal credit, were weak. Crop farming was the main strategy, though many integrated livestock production, petty trading, and other non-farm activities. Large-scale land acquisition led to reduced reliance on crop farming but prompted livelihood diversification, which simultaneously increased vulnerability due to reliance on less secure, low-income activities. Nearly 49% of respondents faced high socioeconomic vulnerability, particularly in livelihood, institutional, economic, and food security dimensions. Respondents generally felt that livelihood diversification could mitigate socioeconomic vulnerability by offering alternative income sources. The study suggests strategies such as fair compensation, participatory land acquisition, livelihood restoration programs, improved access to credit, and skills development as essential for affected farmers.