| Acacia collinsii Saff., 1910 |
| Acacia compacta Rose, 1903 |
| Acacia constricta Benth., 1852 |
| Acacia constricta var. constricta Benth., 1852 |
| Acacia constricta var. vernicosa (Britton & Rose) L.D. Benson, 1943 |
| Acacia conzattii Standl., 1919 |
| Acacia cookii Saff., 1910 |
| Acacia cornigera (L.) Willd., 1806 |
| Acacia cornigera var. americana DC., 1825 |
| Acacia coulteri Benth. ex A. Gray, 1852 |
| Acacia coulteri var. coulteri Benth. ex A. Gray, 1852 |
| Acacia coulteri var. durangensis (Britton & Rose) L. Rico, 2007 |
| Acacia crassifolia A. Gray, 1854 |
| Acacia crinita Brandegee, 1905 |
| Acacia cubensis Schenck, 1913 |
| Acacia cuernavacana (Britton & Rose) Sandwith, 1936 |
| Acacia cumanensis Humb. & Bonpl. ex Willd., 1806 |
| Acacia cuspidata Schltdl., 1838 |
| Acacia cyanophylla Lindl., 1839 |
| Acacia cylindriflora M. Martens & Galeotti, 1843 |