Over the last few years, there has been significant interest in the design of new high strength steels with complex microstructures and the manipulation of their properties at the nanoscale. Understanding the effects of alloying additions on the nanoscale level is essential for tailoring the steel composition and properties for a specific product requirement. Atom probe tomography plays an important role in the characterisation of the microstructural features at the atomic level. This powerful technique has been used for the direct experimental observations of early stages of phase transformations, clustering, fine precipitation, atmospheres around dislocations and segregation to boundaries. An overview on recent advances in the application of atom probe tomography to study thermomechanically processed transformation-induced plasticity steels and nanocrystalline bainitic steels is presented.