Placebo will be administered as SC injection.

Change from baseline in absolute PASI score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups.

Percentage of participants achieving PASI 75 score (participants who achieve >=75% improvement in PASI score) at Weeks 16, 24 and 48 will be reported in guselkumab versus the placebo group. PASI is a common clinical tool used to measure the severity and extent of psoriasis. The PASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of disease of the palms and/or soles.

Percentage of participants achieving PASI 90 score (participants who achieve >=90 % improvement in PASI score) at Weeks 16, 24 and 48 will be reported in guselkumab versus the placebo group. PASI is a common clinical tool used to measure the severity and extent of psoriasis. The PASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of disease of the palms and/or soles.

Percenatge of participants who achieving PASI 100 score (participants who achieve >=100 % improvement in PASI score) at Weeks 16, 24 and 48 will be reported in guselkumab versus the placebo group. PASI is a common clinical tool used to measure the severity and extent of psoriasis. The PASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of disease of the palms and/or soles.

Change from baseline in ppQLI score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. ppQLI assesses relevant dimensions affected by palmoplantar psoriasis (pain/discomfort, functionality, and social/activity limitations) to assess quality of life.

Change from baseline in DLQI score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. DLQI a 10-item questionnaire that can be used to assess overall quality-of-life.

Change from baseline in EQ-5D- 5L score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. EQ-5D-5L is a standardized instrument to measure health-related quality of life.

Change from baseline in ppIGA score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups to assess psoriasis overall lesions.

Change from baseline in f-PGA score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups to assess fingernails separately for nail bed and nail matrix for signs of disease.

Percentage of participants who achieve ppPASI75 response, defined as improvement >=75% in the ppPASI score at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. The ppPASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of disease of the palms and/or soles.

Percentage of participants who achieve ppPASI90 response (participants who achieve >=90 % improvement in the ppPASI score) at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. The ppPASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of the affection of the palms and/or soles.

Percentage of participants who achieve ppPASI100 response (participants who achieve >=100 % improvement in the ppPASI score) at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. The ppPASI is an assessment tool based on the PASI that assesses erythema, pustules, desquamation and the extent of the affection of the palms and/or soles.

Change from baseline in WPAI: PSO score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. WPAI-PSO is a questionnaire which includes 6 questions to measure work productivity and activity impairment related to skin psoriasis.

Change from baseline in NRS:P score at Week 16 will be reported in the guselkumab versus placebo group and at Weeks 24 and 48 will be reported separately for guselkumab and placebo-crossover groups. NRS:P is a self-administered scale that assess pain intensity in participants.

An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product.