Background: Several instruments for measuring nurse professional competence have been tested in different countries and shown to be both reliable and valid. However, there remains a lack of shorter, validated instruments suitable for use in different countries, in large-scale research settings and for longitudinally tracking trends and educational interventions. Aim: The aim of this study was to develop and validate two shortened versions of the Nurse Professional Competence (NPC) Scale, comprising items across the six established competency factors. Design: A cross-sectional, methodological study design, with two secondary data analyses, was conducted. Participants: Participants with NPC data were 612 Swedish registered nurses and 2135 Chinese registered nurses. Methods: Items were selected from the 35-item scale (NPC-35) based on highest corrected item–total correlations, theoretical considerations, and discussions within the research group. Two versions were developed: a 6-item scale (NPC-6) and a 12-item scale (NPC-12). NPC-6 intended to be used only as a total score and NPC-12 to be used both as a total score and as factor scores. The psychometric properties of the shortened scales were evaluated by examining their associations with NPC-35, as well as their reliability and validity. Results: The Swedish and Chinese NPC-6 and -12 scales contained the same items and showed strong associations with the NPC-35 scale (r = 0.925–0.990), after removing overlapping items. Both versions had high internal consistency, with Cronbach's alpha and McDonald's omega values ranging from 0.86 to 0.98. Principal component analyses, using one factor/total scale, indicated that the Swedish and Chinese NPC-12 scales explained 55% and 81% of the variance, respectively, while the NPC-6 scales explained 60% and 82%, respectively. Tests of known-groups validity showed statistically significantly higher scores, NPC-6 and -12, among specialist nurses than non-specialist nurses. Confirmatory factor analyses of the NPC-12 confirmed the original factor structure with six competency factors. Conclusions: The findings indicate that the NPC-6 is a psychometrically acceptable instrument in both countries and the NPC-12 in China when used among registered nurses. The Swedish NPC-12 explained only 55.3% of the variance in nurse professional competence when used as a total score and needs further testing. However, the six competency factors of the NPC-12 might be used instead, as indicated by factor analyses. NPC-6 is intended for total score use only, whereas NPC-12 can be scored using both total and factor scores. Additional psychometric testing is warranted to confirm structural stability, test-retest reliability, and sensitivity to change in different settings and samples.