What a difference a presidential portrait makes. Two years ago, Amy Sherald’s painting career was slowly if belatedly picking up steam. She was 44 and after a four-year hiatus from art — for family illness and her own heart transplant — had had a handful of solo shows, including a four- day pop-up affair on New York City’s Lower East Side in March 2017.

A few months later, in October, Ms. Sherald’s profile began to rise when the National Portrait Gallery commissioned her to paint a portrait of the former first lady Michelle Obama, setting the artist on the fast track to prominence. And so here we are: Ms. Sherald is having her first full-fledged New York solo in the Chelsea space of the voracious mega-gallery Hauser & Wirth. “Amy Sherald: The Heart of the Matter...” is a magnificent, stirring show.

Startlingly spare, in an enormous space, it shows off to good effect Ms. Sherald’s smoldering yet self-contained brand of portraiture, paintings of confident, black people whose stylish clothes and backdrops contrast with their faces, which are uniformly grisaille.

The neutral grayish tones give Ms. Sherald’s subjects a timelessness — we have always been here, deep in history, they seem to say — and reflects her attraction to old photographs. She also uses grisaille, she has said, because she wants to take race out of her paintings. In addition it conjures the early photographs by which black people, having been largely excluded from painting, joined American visual culture.