Wiesemann was born in Herford, North Rhine-Westphalia in the archdiocese of Paderborn.

He later served as a priest in Bösperde, a suburb of Menden and provost of St. Petrus and Andreas in Brilon.

In 2002 Pope John Paul II named him Auxiliary bishop, to which he was ordained on 8 September 2002 in Paderborn Cathedral.

On 19 December 2007 Pope Benedict XVI named him the successor to bishop Anton Schlembach.

[2] He promised to respect the consciences of priests who refuse to bless the unions, while asking them to refer the couples to the diocesan office.