This paper provides an in-depth review of the natural colourants covering their classifications, sources, extraction techniques, application techniques in relation to different textile fibres and their advantages and challenges. The academic readers will find here an overview of the latest developments in extraction and application techniques of a variety of natural colourants. Almost all commercially produced natural fibres and the major synthetic fibres are found to be dyeable and printable with natural colourants. Although the production of natural colourants offers a lot of environmental benefits, their application techniques in textile colouration are not always sound for environment due to the need of synthetic mordants in colouration process. Advances in modern agriculture and biotechnology can play a key role in sorting the limitations of natural colourants and at the same time more and more investigations are still required to establish their cleaner application on textiles.