A woman in a black dress sits turned in profile on a turquoise-blue settee, her head facing to the right and her left arm resting along the curved wooden back of the furniture. Her pale skin stands out against the deep tones of her dress and the seat, while the background dissolves into loose washes of blue and grey. The sitter’s reddish-brown hair is gathered into a neat bun at the back of her head, with a few wisps softly framing her profile.

The artist uses swift, fluid brushstrokes, especially in the dress and background, where colors bleed and merge, creating a sense of atmosphere rather than precise detail. Only the face and arms are rendered with crisp contours, while the rest of the composition is treated with a loose, almost sketch-like quality. The composition places the figure off-center, emphasizing the sweep of the settee and the sitter’s elegant posture.

The blue and grey palette is punctuated by touches of warm brown in the wood and hair, lending a restrained harmony to the scene. The light falls from the left, illuminating the sitter’s face and the upper part of her chest, while casting the lower part of the dress and seat into shadow. The sitter's right hand loosely grasps the carved wooden armrest at the lower left, with visible knuckles and fingers outlined in pale washes.

The turquoise upholstery curves around the figure, with subtle variations in color indicating the folds and shadows of the fabric. In the upper right corner, the background transitions to a lighter, almost beige wash, contrasting with the cooler blue tones elsewhere. The wooden frame of the settee is rendered in loose, reddish-brown strokes, visible at both the left and right edges of the composition.

Soft, diffuse light creates a gentle highlight along the sitter's left shoulder and arm, while the right side of her face and neck remain in shadow. Madame Gautreau (Madame X) is made by John Singer Sargent in 1883.