Understanding of nitrogen (N) and phosphorus (P) allocation patterns among various plant organs and tissues is crucial for gaining insights into plant growth and life-history strategies, as well as ecosystem nutrient cycles. However, there is limited information available regarding allocation strategies for N and P in bark (i.e., all tissues external to the vascular cambium), which is an indispensable and specialized secondary tissue system. This study presents analyses of a newly compiled and comprehensive data set comprising 1246 pairwise N-P observations across 335 tree species spanning 557 independent sampling sites worldwide. The aim is to explore the interspecific N and P stoichiometry of bark. The global geometric means for bark N and P concentrations, as well as N:P ratios, were 3.88 mg/g, 0.2 mg/g, and 19.38, respectively. However, these values varied significantly among different functional plant-groups and biomes. Across all 335 species, the N vs. P scaling exponent was 0.69 for bark, which is similar to the 2/3-power scaling relationship observed in leaves and twigs. However, the bark N vs. P scaling exponent differed among functional plant-groups, biomes, and local sites, indicating the absence of a “canonical” scaling exponent. The interactions of soil total N and P collectively accounted for the most significant variation in the bark scaling exponent among local sites. The results indicate that there is no “canonical” bark N vs. P scaling exponent, and that soil nutrient content is the most important factor influencing N and P allocation strategies in bark. These findings may hold significant implications for predicting plant nutrient allocation strategies in response to environmental changes.