What are the chances of the same pop music legend appearing in the works of two unrelated artists showing concurrently in Chelsea galleries? Slim, you might think. And yet it has happened to the self-styled “hardest working man in show business,” James Brown.

His smiling, singing visage is collaged into a painting by Chris Martin, “Homage James Brown Godfather of Soul” (2001–07), in Mr. Martin’s first show with Mitchell-Innes & Nash, while the words “James Brown is Dead” appear in a 22-foot-long collage of that title in Mark Bradford’s show at Sikkema Jenkins, his second at that gallery. In Mr. Bradford’s work, the words were incised on, and peeled away from, the top layer of an appropriated billboard of old posters.

Brown is the appropriate icon to unite these two artists, for he had a protean, genre-bending ability to be at once lyrical and raucous, to simultaneously convey defiance and joy — hallmarks of these energetic exhibitions. Mr. Bradford and Mr. Martin are both bricoleurs not just in terms of medium — Mr. Bradford uses materials gathered from the vicinity of his South Central Los Angeles studio; Mr. Martin folds found objects and unlikely materials into his paintings as applications or supports — but in spirit as well. They both manage to convey at the same time a certain nonchalance, a throw-away, happy-go-lucky, grab-what-you-can aesthetic while also unabashedly making work of pictorial and emotional ambition. Recalling Brown’s joyous shout, these artists have a Midas touch with mess.

Mr. Bradford’s show coincides with the inclusion, this month, of a gigantic work of his, “Helter Skelter” (2007) at the New Museum’s inaugural four-part show, “Unmonumental,” an ironic title in view of the scale of his work and the apotheosis it represents for him. While it is true that his chosen materials are unprepossessing and redolent of litter and decay, the transformations they undergo have an element of the heroic about them, both in terms of energy of application and how the finished image reads. He creates wayward, pulverizing grids that recall urban maps, layering large parts of the composition with silver leaf. This latter material continues rather than resolves the ambiguity of Mr. Bradford’s collage as the effect can be read equally in terms of luxury or the commonplace, because of the resemblance to aluminum machinery.

“Giant” (all 2007), the first work you see, is the most literally cartographic. Like an urban street plan where neighborhoods contiguous to the one under view are shadowed out, the painting has a central shape in black and colors and surrounding areas lightly denoted in incised lines on white. The detailed area is a mass of differing kinds of notation. There are elements of virtually unmediated collage — you can almost read the newspaper ads in places. Then there are city blocks of bright red. Streets and roads are differentiated not just in thickness but in application, too: The bigger roads are looser and more gestural than the tightly gridded-up residential streets, which are laid down with a meticulous hand.

By the time you get to “Boreas” in the main gallery, the map associations have melted into near ethereal abstraction. The roads are like spaghetti, in dark, dense colors, and the outlying district is glossy silver.

Each work, in fact, has its own pictorial logic. In “Let’s Make Christmas Mean Something This Year,” the map goes berzerk in a whirling gestalt of textured, hairlike black lines. In “Orbit,” a collaged baseball hovers over a tight city grid. There is also a sculpture made from a stack of cartons of stereo equipment, with the texts and graphics picked out in the artist’s expressive hand. The common trait uniting this disparate array of images — besides the artist’s winning exuberance — is a discovery of order within an anarchic mass.

Even more than Mr. Bradford, Mr. Martin has the endearing distinction of painting a one-man group exhibition. The Brooklyn-based artist has been exhibiting in New York since 1988. Even though his 2005 show in Williamsburg’s Sideshow Gallery contained monumentally scaled works, there seems to be a new sense of ambition in this group, although there is in the goofy, scrappy nature of his surfaces a retention of the bohemian spirit as well. The use of language in his work — both what is said and how it is written — has the energetic insolence of a James Brown lyric. “Good Morning Alfred Jensen Good Morning” (2005–07) has the words of its title in white block letters above an arced rainbow of colors, redolent of a Jensen painting, with the collage of a smiling blond in a blue bikini at its center. Jensen is also alluded to in a strikingly simple painting of a star form against a black ground in “Seven Pointed Star” (2007).

“Broom Painting” (2007) has a striated loop, clearly done as the title implies with a broom, ploughing into a more conventionally applied landscape beneath in a way that retains a shadow of the original composition and its discrete areas of bright color while creating an audacious mush. “Afghan Painting” (2007) is daubed in reds, greens, and yellow on a found fabric with collaged elements of frogs in differing scales. The relatively less experimental works in the show, however, are arguably the more resonant. “Untitled” (2007) has two stacks of blue discs, several with white discs at their center, flanked by vertically bisected stacks of yellow discs, against a red ground. The painting is done on top of several actual, randomly placed circular forms that protrude from the picture plane. The painted discs are all somewhat crudely, though by no means hastily, drawn. The energy derives from the negative space, popping forward in red, and from the points where the discs join.

The result is a telling mix of faux primitivism and sophisticated effect. You can contemplate it at leisure or walk away quickly with a smile. James Brown is not dead.

Bradford until February 23 (530 W. 22nd St., between Tenth and Eleventh avenues, 212-929-2262).

Martin until March 1 (534 W. 26th St., between Tenth and Eleventh avenues, 212-744-7400).