Parts 1-3:

• Muscle-invasive or recurrent, non-muscle-invasive urothelial carcinoma of the bladder
• For selected Cohorts: Activating tumor pan-fibroblast growth factor receptor (FGFR) mutation or fusion, as determined by local or central testing, approved by the sponsor prior to the start of study treatment. Local tissue-based results (if already existing) from next-generation sequencing (NGS) or polymerase chain reaction (PCR) tests performed in Clinical Laboratory Improvement Amendments (CLIA) -certified or equivalent laboratories, or results from commercially available PCR or NGS tests
• Cohorts 1 and 2: Bacillus Calmette-Guérin (BCG) experienced, or participants with no BCG experience because BCG was not available as a treatment option in the participant's location within the previous 2 years and is currently unavailable. Participants who received an abbreviated course of BCG due to toxicity are still eligible
• Cohort 1 only: Refuses or is not eligible for radical cystectomy (RC)
• Cohorts 2 and 4: Willing and eligible for RC

Part 4:

• Have histologically confirmed diagnosis of recurrent Intermediate-risk-non-muscle invasive bladder cancer (IR-NMIBC) Ta LG tumors
• Must not have undergone tumor debulking or selective ablation of visible lesions; partial tumor biopsy to confirm diagnosis and provide tissue for biomarker testing is permitted as long as remaining tumor is at least 5 millimeter (mm) in size
• Must submit tissue and urine for FGFR testing
• Can have a prior or concurrent second malignancy which natural history or treatment is unlikely to interfere with any study endpoints of safety or the efficacy of the study treatment

Parts 1-3:

• Concurrent extra-vesical (that is, urethra, ureter, renal pelvis) transitional cell carcinoma of the urothelium
• Prior treatment with an pan-fibroblast growth factor receptor (FGFR) inhibitor
• Received pelvic radiotherapy <=6 months prior to the planned start of study treatment. If received pelvic radiotherapy greater than (>)6 months prior to the start of study treatment, there must be no cystoscopic evidence of radiation cystitis
• Presence of any bladder or urethral anatomic feature that in the opinion of the investigator may prevent the safe use of Erdafitinib intravesical delivery system
• Indwelling urinary catheter. Intermittent catheterization is acceptable

Part 4:

• Histologically confirmed diagnosis of T1 NMIBC, HR NMIBC (HG/G2 or HG/G3 or CIS) or MIBC, locally advanced, non-resectable, or metastatic urothelial carcinoma at any time prior to enrollment. Previous high grade (HG) disease is accepted as long as diagnosis date is greater than or equal to (>=5) years ago and there is documentation of low grade (LG) Ta thereafter
• Known allergies, hypersensitivity, or intolerance to any study component or its excipients
• Has a current diagnosis of newly diagnosed IR-NMIBC
• Received an investigational treatment for bladder cancer after Transurethral Resection of the Bladder Tumor (TURBT) for the current NMIBC diagnosis or within 4 weeks or the agent/therapy washout period, whichever is longer, before the planned first dose of study treatment, or is currently enrolled in an investigational study
• Evidence of current bladder perforation by cystoscopy or imaging