Plants essentially contribute to the strength of soil and, in particular, steep slopes susceptible to erosion and shallow landslides. The corresponding functions of vegetation significantly control processes above and below ground such as interception, evapo-transpiration, soil aggregation and root reinforcement. Either way, they are all correlated with plant growth. Consequently, in order to unfold their soil stabilising potential, the plants must grow and sustainably survive. However, what sounds so obvious is anything but given under the often hostile conditions dominating on bare and steep slopes. This is exactly the point where mycorrhizal fungi come into play, known to improve the plants’ ability to overcome periods governed by strongly (growth) limiting factors. Within this scope, numerous investigations have been conducted in order to understand and quantify mycorrhizal effects on different plant and soil functions related to eco-engineering and, particularly, to soil and slope stability. Results on plant growth and survival as well as on soil aggregation and slope stabilisation are presented and discussed from a mycorrhizal perspective.