He will remain in his creative role with the company, which says he will continue to shape collections alongside Domenico Dolce, a partnership that has defined the brand's identity for four decades.
Gabbana, 63, will be replaced by chief executive Alfonso Dolce, brother of co-founder Domenico, who will take on the role from January 1.
Filings show Gabbana notified the company of his decision in December.
Gabbana is understood to be considering options regarding his shareholding, though he remains closely involved in the brand's future.
It comes shortly after Dolce & Gabbana celebrated its 40th anniversary and at a moment of transition for the Milan-based label, which has in recent years expanded beyond the runway into hospitality, interiors and immersive brand experiences.
Industry reports have also pointed to ongoing discussions with lenders and the possibility of fresh investment, as the wider luxury sector adjusts to changing global demand.
Founded in Milan in 1985 by Dolce and Gabbana, the brand rose to prominence with a bold and quintessentially Italian vision of glamour.
The men quickly became known for their celebration of Mediterranean sensuality, defined by corsetry, inky lace and blooming black florals with references to Sicilian culture, Catholic iconography and Italian cinema.
Their aesthetic struck a chord internationally during the late 1980s and 1990s, helping to define an era of maximalist fashion.
A pivotal moment in the brand's rise came through its association with Madonna, who famously wore Dolce & Gabbana during the 1990s and commissioned the designers to create costumes for her 1993 Girlie Show tour.
The collaboration cemented the label's reputation for provocative, body-conscious design and aligned it with global pop culture at its most influential.
The house has maintained strong ties with celebrity and entertainment, dressing a range of exclusive figures across music, film and pop culture.
Today, Dolce & Gabbana spans ready-to-wear, accessories, beauty and haute couture, with its Alta Moda and Alta Sartoria collections showcasing the highest levels of Italian design.
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