Infections caused by Candida species have increased significantly in the past decades and are among the leading causes of morbidity and mortality worldwide, resulting in serious public health problems. Currently, conventional antifungals are often ineffective as Candida spp. have developed growing resistance to systemic drugs. Since inorganic metallacarboranes are known to affect cellular events, new derivatives of these abiotic compounds were tested against Candida albicans. Compounds based on cobalt bis-dicarbollide [COSAN] were studied on Candida albicans strains, including a panel of 100 clinical isolates. The presented data prove that metallacarborane derivatives are effective against clinical isolates of Candida albicans, even those resistant to systemic drugs, and show synergistic potential in combination with amphotericin B, and low toxicity against human cells and Danio rerio embryos. This paper is a consequential step in the investigations of the broad spectrum and valuable future medical applications of metallacarboranes, especially in the fight against drug-resistant pathogens.