For the past five years, Jack Sivan has been running a small tailoring and men’s wear business out of the Brooklyn apartment he shares with his wife and three guinea pigs (Bagel, Panda and Faun). Recent events have had him thinking about working someplace other than his home.

Mr. Sivan’s namesake brand received outsize exposure this year when the actor Ato Essandoh, a star of the Netflix series “The Diplomat,” wore a custom tuxedo to the Screen Actors Guild Awards in February. The ensemble included a cropped midnight blue jacket with satin lapels, a crisp white button-up shirt, a black bow tie and a long pleated skirt that nearly fell to the floor.

“When I put it on, it just felt good,” Mr. Essandoh said in an interview, adding that his stylist, John Tan, had introduced him to Mr. Sivan. “Sometimes you wear something and it feels right,” the actor said. “It felt regal and I loved the way that it flowed.” The tuxedo caught the attention of Mr. Essandoh’s peers like his “Diplomat” castmate Keri Russell and the “Abbott Elementary” actress Sheryl Lee Ralph, he said, who stopped him and “was like, ‘Boy, look at what you’re wearing!’”

Not long before dressing Mr. Essandoh, Mr. Sivan landed his first wholesale account with Ford General, a store in Chicago. In May, it will start selling pieces from Mr. Sivan’s burgeoning ready-to-wear line, which includes items like a double-breasted linen blazer ($1,155), striped linen pants ($575) and a matching military-inspired jacket ($685).

Mr. Sivan’s custom suits start at about $2,200; their prices vary based on fabrics and other factors. His business has taken over much of the living room in his apartment near Prospect Park, which has workstations with sewing machines and metal shelves where materials and clothing patterns are stored. There are also multiple mannequins that Mr. Sivan, 28, dresses in clothes he is making, which on a recent visit to the space included a pinstripe chore coat made of Italian shetland flannel wool and a brown coat that still had sewing pins in a pocket and the collar.