The 1973 U.S. Professional Indoor was a men's tennis tournament played on indoor carpet courts at the Spectrum in Philadelphia, Pennsylvania in the United States that was part of the 1973 World Championship Tennis circuit.

It was the sixth edition of the tournament and was held from February 6 through February 11, 1973.

Third-seeded Stan Smith won the singles title.

Stan Smith defeated Robert Lutz 7–6(7–2), 7–6(7–5), 4–6, 6–4 Brian Gottfried / Dick Stockton defeated Roy Emerson / Rod Laver 4–6, 6–3, 6–4