He migrated to Australia on the Mary Sharp arriving 11 June 1844, afterwards gaining a few years of colonial experience working for David Perrier at Bathurst.

[2][3] In 1850, following the murder of settler Gregory Blaxland, Walsh participated in a massacre of indigenous people on Paddy's Island,[4] details of which he would give during Queensland parliamentary debate several decades later.

During this venture he and his men made their mark on Queensland history as the first whites to 'blaze the track' of what is now the section of Bruce Highway between Degilbo in the Burnett to the Boyne Valley at Port Curtis, now Gladstone.

[6] Afterwards he settled initially as the part owner, later sole proprietor of the vast Monduran and Degilbo stations, setting up the latter as a domicile for himself and his growing family.

Walsh is equally well known for his defence for the Queensland's sugar industry and its use of Melanesians, so-called Kanaka, labour and dismissal that the accusation of this as slavery was anything more than working-class prejudices.