He will replace Bruno Saelzer, who quit as managing board chief of Hugo Boss in February amid differences of opinion with Permira, the British investment fund that gained control of 80 percent of the group in mid-2007.
Senior staff have accused Permira of pillaging the company by pressing managers to pay high dividends to make a rapid return on its investment.
The tension has also triggered the resignation of the head of the Hugo Boss supervisory board, Guiseppe Vita, who praised the appointment of Lahrs.
"With his international experience in leading brands of the high-end and luxury sector of the fashion industry and his expertise in distribution, he fills all the management conditions to bring to Hugo Boss (...) a new stage of development," Vita said.
Lahrs, of German origin, has worked for French luxury products group LVMH for 12 years.