The background of this study is the observation that people with high emotional intelligence (EI) perform well at work. The aim of this study was to further validate the Trait Emotional Intelligence Questionnaire Short Form (TEIQue-SF) by (1) investigating its relationships with the Mini International Personality Item Pool-6 Inventory (Mini-IPIP6), the Short Dark Triad Assessment (SD3), and the Individual Work Performance Questionnaire (IWPQ), (2) identifying which personality traits best explain variations in trait EI, and (3) investigating whether trait EI can predict variations in each dimension (Task Performance, Contextual Performance, and Counterproductive Work Behavior, CWB) of self-perceived work performance. A cross-sectional study was done with 228 Swedish participants (M = 34 years, SD = 12.6, range 16-71 years, 66% women) with an average work experience of 14 years (SD = 11.5). One expected result was that all dimensions of trait EI correlated negatively with Neuroticism and Machiavellianism, and positively with Extraversion, Agreeableness, Conscientiousness, Openness to Experience, and Narcissism. Self-control and Sociability had, however, almost zero correlation with Machiavellianism. A positive correlation was found between all dimensions of EI and Task Performance and Contextual Performance. Standard regression analyses showed that 26% to 46% of the variation in the different dimensions of EI was explained by the “Big Six” personality traits. Hierarchical multiple regression analyses indicated that trait EI accounted for a significant proportion of the variation in Contextual Performance that was not explained by any of the “Big Six” personality traits, and that trait EI did not explain any variation in CWB above Neuroticism and Honesty-Humility. In addition, trait EI explained an additional 6% of the variation in Task Performance when controlling for gender, age, Neuroticism and Conscientiousness. It is concluded that the Swedish version of the TEIQue-SF has shown reasonable theoretically and empirically grounded relationships with relevant variables for the workplace.