A common approach to enhance the self-healing behaviour of cracked backfill is through the addition of carriers, but this practice can potentially disrupt the overall performance of the backfill and pose environmental concerns. Overcoming the limitations of traditional carrier-based methods to improve self-healing efficiency has been a challenging task. This study proposed an environmentally friendly approach to enhance the healing ratio of cracked backfill without the need for additional carriers. Specifically, a mixture of aerobic and anaerobic bacteria was pre-embedded in polypropylene-fiber reinforced backfill. The self-healing capacity of the cracked backfill was systematically evaluated in terms of crack width and area healing efficiency, strength recovery ratio, permeability coefficient, and water absorption. The results showed that the incorporation of mixed bacteria in the backfill resulted in an area healing ratio of 44.71% and a strength recovery ratio of 30.88%. The mixed bacteria had a higher biomineralization ratio compared to the noted single strain, suggesting its enhanced capacity in self-healing. Also, the mixed bacteria exhibited higher sustainability in self-healing. These findings provide compelling evidence that the self-healing ratio of cracked backfill can be improved through a benign approach that only involves pre-embedding mixed bacteria without the use of additional carriers.