In the summer of 1918 he witnessed a priest of the Order of Preachers give a sermon in the Alba Cathedral and Girotti became enthralled to the point where he set his heart on becoming a priest himself.
He worked as a professor at theological studies at the Saint Maria della Rose convent of his order in Turin but liked to often aid the old at a hospice not too far form his convent; one of his students was Father Giacinto Bosco.