Am dros 20 mlynedd, cyn dod yn Ysgrifennydd Cyffredinol TUC Cymru, roedd Martin yn swyddog undeb llafur llawn amser mewn nifer o ddiwydiannau, gan gynnwys gweithgynhyrchu uwch a gwasanaethau iechyd. Cyn hynny, gweithiodd ym maes addysg bellach ac ymchwil sgiliau diwydiannol. Rhwng 2003 a 2005, roedd yn gynghorydd arbennig ar ddatblygu economaidd i’r Prif Weinidog a’r Cabinet.
For over twenty years before becoming Wales TUC General Secretary, Martin was a full time trade union official covering a wide range of industries including advanced manufacturing and health services.  Before that he worked in further education and industrial skills research. In 2003-2005 he served as economic development special advisor to Wales’ First Minister and Cabinet.