Scrub the rusted furniture with a wire brush and soapy water to remove any flaking rust. Don't worry about removing all the rust; just focus on the flaking and chipping parts of the furniture.
Rinse the furniture with a garden hose, and dry it thoroughly with a towel when you finish scrubbing.
Sand the furniture with 80- to 100-grit sandpaper to smooth any rough spots on the surface. Wipe the furniture with a tack cloth after sanding to ensure it is completely clean.
Apply a rust-inhibiting spray primer to the furniture, and let it dry overnight. This primer will seal the existing rust and prevent new rust from forming.
Spray paint the outdoor furniture with an oil-based spray paint appropriate for use on metal.
Apply a second coat of spray paint when the first one is completely dry. When the second coat of paint dries, your furniture is ready to use.