The nutrient use efficiency of perennial ryegrass (Lolium perenne L.) (PR) and white clover (Trifolium repens L.) (WC) cultivars can affect the grass-legume compatibility of different cultivar combinations, thus impacting the sustainability of animal production systems, especially on marginal soils. The objective of this work was to evaluate N, P, and K absorption efficiency (NAE, PAE, and KAE) and use efficiency (NUE, PUE, and KUE). This study included two experiments with the same full factorial treatment structure (4 PR cultivars × 3 WC cultivars) in a randomized complete block design under field conditions and a completely randomized pot design. The field cutting experiment was carried out on sites with two contrasting soil depths and the pot experiment was conducted under shade conditions. Results showed nonsignificant (P > 0.05) factor interactions for DM yield and both nutrient absorption and use efficiency. The NAE and PAE of PR ‘Extreme’ and ‘Bealey’ were higher under field conditions than pot conditions. In the field experiment, NAE of WC ‘Will’ (2.33 kg DM ha-1/mg N kg-1) tended to be similar (P < 0.05) to other cultivars in deep soil, but was significantly higher (P < 0.001) than ‘Ladino’ and ‘Bounty’ in shallow soil (0.70 kg DM ha-1/mg kg-1). The evaluation of NUE and PUE under field conditions and KUE under pot conditions showed that PR ‘Bealey’ and WC ‘Ladino’ reached higher values. In conclusion, results showed a cultivar effect on nutrient use efficiency in PR/WC mixtures, which had an impact on PRWC compatibility, mainly due to the higher absorption efficiency of PR ‘Bealey’ and WC ‘Will’, both of which exhibited the highest degree of compatibility for total DM yield.