Participants will receive JNJ-78934804 dose regimen 2 SC. All participants who meet inadequate response criteria will be escalated to an active treatment. Participants who are eligible and willing to continue the study intervention that they are receiving at Week 44 may enter the long-term extension.

Participants will receive JNJ-78934804 dose regimen 3 SC. All participants who meet inadequate response criteria will be escalated to an active treatment. Participants who are eligible and willing to continue the study intervention that they are receiving at Week 44 may enter the long-term extension.

Golimumab will be administered as subcutaneous injection.

JNJ-78934804 will be administered subcutaneously as per defined regimen.

Placebo will be administered as subcutaneous injection.

Percentage of participants with symptomatic remission at Week 48 will be reported. Symptomatic remission at Week 48 based on stool and rectal bleeding symptoms.

Percentage of participants with combination of histological remission and endoscopic improvement at Week 48 will be reported. Histologic remission and endoscopic improvement at Week 48 based on the histologic grading and the Mayo endoscopy subscore.

Percentage of participants with clinical remission at Week 48 will be reported. Clinical remission based on the modified Mayo subscores will be reported.

An AE is any untoward medical occurrence in a clinical study participant administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention.

A SAE is any untoward medical occurrence that at any dose: results in death; is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant disability/incapacity; is a congenital anomaly/birth defect; is a suspected transmission of any infectious agent via a medicinal product; is medically important.

Laboratory parameters over time will be reported.

Vital signs parameters over time will be reported.

The C-SSRS scale consists of 28 items in 4 sections: suicide behavior, actual attempts, suicidal ideation, and intensity of ideation. Worsening of suicidal ideation was an increase in severity of suicidal ideation from baseline.

Serum concentrations of guselkumab over time will be reported. Serum samples will be analyzed to determine concentrations of guselkumab using a validated, specific, and sensitive method.

Serum concentration of golimumab over time will be reported. Serum samples will be analyzed to determine concentrations of golimumab using a validated, specific, and sensitive method.

Percentage of participants with antibodies to guselkumab will be reported.

Titers of antibodies to guselkumab will be reported.

Percentage of Participants with Antibodies to golimumab will be reported.

Titers of antibodies to golimumab will be reported.

Percentage of participants with neutralizing antibodies to guselkumab will be reported.

Percentage of participants with neutralizing antibodies to golimumab will be reported.