Introduced species encounter novel biotic and abiotic conditions that influence their success in new environments. Their advantage is often linked to reduced competition from native species that lack eco-evolutionary experience, as well as to their ability to pre-empt resources. Once established, their success can also be shaped by changes in soil conditions, particularly through interactions with soil microbial communities. Understanding how these factors influence invasion success can provide valuable insights into predicting future invasions under global change. In this study, we examined how eco-evolutionary experience and soil bacterial communities influenced the performance of the invasive subshrub Senecio inaequidens DC. We conducted a fully factorial experiment in growth chambers consisting of two factors: competing community identity with three levels (plant species from its native range (South Africa), from its invasive range (Italy) and a control with only S. inaequidens) and soil biota conditions with two levels (wild soil and autoclaved soil with lower microbial load). Our results showed that plant community identity had the strongest effect on S. inaequidens growth (height and lateral spread), with the smallest individuals occurring in competition with South African species. Growing on autoclaved soil had no major impact on plant height, suggesting that reduced competition played a greater role than soil bacterial differences in determining plant performance. Suppression was stronger when the competing native species were more closely related to S. inaequidens. Soil bacterial communities were influenced by both plant identity and soil treatment, and S. inaequidens performed better in soils with lower bacterial diversity, possibly due to reduced pathogen pressure. These findings suggest that invasive species management could be improved by fostering competition with evolutionarily experienced native species and maintaining or enhancing soil microbial diversity to limit invader success.