Gilliam’s metal sculptures, part of his broader oeuvre from the 1980s and 1990s, were developed for public commissions, marking a significant period where Gilliam expanded his material and formal explorations to include painted metal. This diversification reflected his ongoing interest in challenging the boundaries of traditional painting and sculpture​ (The Museum of Modern Art)​.

Recognition of Gilliam’s contributions to art, though slow in coming, eventually became significant. He received numerous awards, including a Guggenheim Foundation fellowship, the Mississippi Governor's Award for Excellence in the Visual Arts, and the U.S. State Department Medal of Arts, highlighting his impact on and contributions to the visual arts. In 2021, he was honored with a Distinguished Honour Award at Washington D.C.'s 36th Annual Mayor's Arts Awards for his extensive contributions to the arts and culture of the District of Columbia over two decades or more​ (Ocula Art)​.

Gilliam's work has been celebrated in both solo and group exhibitions globally. Notable solo exhibitions include "Sam Gilliam: Full Circle" at the Hirshhorn Museum, "The Music of Color: Sam Gilliam, 1967—1973" at Kunstmuseum Basel, and "Sam Gilliam: a retrospective" at the Corcoran Gallery of Art, among others. His participation in group exhibitions, such as "Soul of a Nation: Art in the Age of Black Power" at Tate Modern, and "With Pleasure: Pattern and Decoration in American Art 1972–1985" at The Museum of Contemporary Art, Los Angeles, further underscores his role in the broader discourse of American art​ (Ocula Art)​.