Interest has increased in comorbidities associated with psoriasis and their effects on health‐related quality of life (HRQoL). This study aimed to evaluate the prevalence of metabolic syndrome (MetS) and psoriatic arthritis (PsA) and to investigate HRQoL and the prevalence of hypertension, type 2 diabetes mellitus (T2DM), obesity and dyslipidemia. In a cross‐sectional design, patients diagnosed with plaque psoriasis answered an interview and standardized questionnaires (Dermatology Life Quality Index questionnaire [
DLQI
], 36‐Item Short Form Health Survey [SF‐36] and EuroQol Five‐Dimension Questionnaire Three‐Level version [
EQ
‐5D‐3L]). Physical examination and several tests to assess desired outcomes were performed by a dermatologist and a rheumatologist during three visits. The prevalence of MetS and PsA was 50.0% and 41.8%, respectively. Dyslipidemia was the most prevalent (74.5%) secondary comorbidity, followed by hypertension (61.8%), obesity (52.5%) and T2DM (30.9%). The mean (standard deviation)
DLQI
score was 6.5 (6.9), and mean physical and mental SF‐36 measures were 45.2 (10.4) and 45.5 (12.3), respectively, and for EQ‐5D‐3L, mean utility index and
EQ
‐
VAS
scores were 0.68 (0.27) and 72.7 (19.7), respectively. PsA and MetS are important comorbidities; a reduced HRQoL is noted among plaque psoriasis patients with these comorbidities, emphasizing the relevance of diagnosis and treatment beyond the care of skin lesions.