Background and aims <p>The supply of exogenous nutrients, such as nitrogen (N) and phosphorus (P), can alter litter and soil organic carbon (SOC) decomposition. The aim of this study was to investigate the interactive effects of nutrient addition and litter input on litter and SOC mineralisation in semi-arid steppe soil under long-term wheat cultivation in Kazakhstan.</p> Methods <p>A 37-day incubation experiment was conducted to assess litter and SOC mineralisation rates in response to N, P, and N and P (NP) addition with or without additional ¹³C-labelled litter (<i>Dactylis glomerata</i> L.).</p> Results <p>In the absence of litter, N, P, or NP addition had no significant effect on SOC mineralisation. In contrast, treatments with litter addition (litter, N + litter, P + litter, and NP + litter) resulted in 24.1%–27.6% mineralisation of litter-derived carbon (C) over the incubation period and induced a positive priming effect (PE). Cumulative litter-derived C emissions decreased by 7.1%, 12.7%, and 12.8% under N, P, and NP treatments, respectively. The PE slightly decreased by 13.4% and 9.2%, respectively, when N and NP were added to the litter compared to litter-only treatment; whereas, P fertilisation slightly increased the PE by 6.6%. One possible mechanism is that the increased N and P availability suppresses litter mineralisation but sustains positive PE by increasing the maximal velocity (<i>V</i>_<i>max</i>) of β-1, 4-N-acetyl-glucosaminidase and decreasing the <i>V</i>_<i>max</i> of phosphatase under N and P addition, respectively.</p> Conclusions <p>The improvement of N and P availability reduces microbial mining of litter C, and the remaining recalcitrant litter C represents a potential SOC resource.</p>