Alien plant species have been introduced by humans or by natural forces globally, and many of them have become invasive. Invasive alien plant species (IAPS) have positive or normally detrimental effects on the ecosystem as they alter the ecosystem’s properties, functions, and associated services. The ecosystem disservices (EDS) linked with IAPS include effects on human health, and threats to native biodiversity, soil, crops, horticulture, forestry, industry and the environment. The IAPS poses serious threats to native flora, especially endemic plants with a narrow distribution range. New pests and allergies become widespread along these IAPS damaging human health, crops and livestock. The ecosystem services (ES) linked to IAPS include the use of hundreds of alien woody species for timber, many species have ornamental, spiritual and aesthetic value, and several are cultivated for pharmaceutical and cosmetic compounds. Other ecosystem services (ES) of IAPS include ecosystem restoration, soil stabilisation, phytoremediation, erosion regulation and windbreaks. IAPS are among the top global environmental challenges and have large-scale environmental and socioeconomic effects. The chapter deconstructs the bifold roles played by invasive alien plants, describing their advantages (e.g., erosion control, pollination) and harm (e.g., invasive effect on native vegetation, economic loss), centered on context-dependent ecological and human trade-offs. IAPS have a major ecosystem disservices (EDS) and services (ES) that directly and indirectly affect human well-being, the environment, and socioeconomic sectors. This chapter discusses the benefits (ecosystem services) and drawbacks (disservices) of alien invasive plants by exploring their ecological and socio-economic impacts. The main discussion includes their role in habitat protection, soil stabilization, nutrient cycling, and the negative effects like biodiversity loss and resource competition. Case studies display the impact of invasive species on ecosystems and human health.