Inclusion Criteria:

          -  Capable of giving signed informed consent.

          -  Male or female, 18 years or older.

          -  Have a confirmed diagnosis of multiple myeloma (MM) as defined by the International
             Myeloma Working Group (IMWG) criteria.

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.

          -  Have been previously treated with at least 1 prior line of MM therapy including a
             lenalidomide-containing regimen and must have documented disease progression during or
             after their most recent therapy.

          -  Must have at least 1 aspect of measurable disease defined as one of the following;

               1. Urine M-protein excretion greater than or equal to (≥)200 milligrams (mg) per
                  24-hour, or

               2. Serum M-protein concentration ≥0.5 grams/deciliters (g/dL) (≥5.0 g/liter [L]), or

               3. Serum free light chain (FLC) assay: involved FLC level ≥10 mg/dL (≥100 mg/L) and
                  an abnormal serum free light chain ratio (less than [<]0.26 or greater than
                  [>]1.65) only if participant has no measurable urine or serum M spike.

          -  Have undergone autologous stem cell transplant (ASCT) or are considered transplant
             ineligible. Participants with a history of ASCT are eligible for study participation
             provided the following eligibility criteria are met: a. ASCT was >100 days prior to
             the first dose of study medication. b. No active bacterial, viral, or fungal
             infection(s) present

          -  All prior treatment-related toxicities (defined by National Cancer Institute Common
             Terminology Criteria for Adverse Events [NCI-CTCAE] version 5.0) must be less than or
             equal to (≤)Grade 1 at the time of enrolment, except for alopecia.

          -  Adequate organ system functions as mentioned in the protocol.

          -  Male and female participants agree to abide by protocol-defined contraceptive
             requirements.

        Exclusion Criteria:

          -  Active plasma cell leukemia, symptomatic amyloidosis or active polyneuropathy,
             organomegaly, endocrinopathy, monoclonal plasma proliferative disorder, and skin
             changes (POEMS) syndrome at the time of screening.

          -  Prior allogeneic SCT.

          -  Systemic anti-myeloma therapy (including chemotherapy and systemic steroids) within 14
             days or five half-lives (whichever is shorter) preceding the first dose of study drug;
             prior treatment with a monoclonal antibody drug within 30 days of receiving the first
             dose of study drugs.

          -  Plasmapheresis within 7 days prior to the first dose of study drug.

          -  Received prior treatment with or intolerant to pomalidomide.

          -  Received prior Beta cell maturation antigen (BCMA) targeted therapy.

          -  Intolerant to bortezomib or refractory to bortezomib (for example; participant
             experienced progressive disease during treatment, or within 60 days of completing
             treatment, with a bortezomib-containing regimen of 1.3 mg/meter square [m^2] twice
             weekly).

          -  Evidence of cardiovascular risk including any of the following;

               1. Evidence of current clinically significant untreated arrhythmias, including
                  clinically significant electrocardiogram abnormalities including second degree
                  (Mobitz type II) or third degree atrioventricular (AV) block.

               2. Recent history within (3 months of screening) of myocardial infarction, acute
                  coronary syndromes (including unstable angina), coronary angioplasty, or stenting
                  or bypass grafting .

               3. Class III or IV heart failure as defined by the New York Heart Association (NYHA)
                  functional classification system

               4. Uncontrolled hypertension.

          -  Any major surgery within the last 4 weeks.

          -  Previous or concurrent invasive malignancy other than multiple myeloma, except:

               1. The disease must be considered medically stable for at least 2 years; or

               2. The participant must not be receiving active therapy, other than hormonal therapy
                  for this disease.

          -  Known immediate or delayed hypersensitivity reaction or idiosyncratic reaction to
             belantamab mafodotin or drugs chemically related to belantamab mafodotin, or any of
             the components of the study treatment.

          -  Evidence of active mucosal or internal bleeding.

          -  Cirrhosis or current unstable liver or biliary disease per investigator assessment
             defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia,
             esophageal or gastric varices, persistent jaundice.

          -  Active infection requiring treatment.

          -  Known human immunodeficiency virus (HIV) infection, unless the participant can meet
             all of the following criteria: a. Established anti-retroviral therapy (ART) for at
             least 4 weeks and HIV viral load <400 copies/milliliters (mL); b. Cluster of
             differentiation (CD)4+ T-cell (CD4+) counts >=350 cells/microliters c. No history of
             acquired immunodeficiency syndrome (AIDS)-defining opportunistic infections within the
             last 12 months.

          -  Participants with hepatitis B will be excluded unless the protocol-defined criteria
             are met.

          -  Positive hepatitis C antibody (Hep C Ab) test result or positive hepatitis C
             ribonucleic acid (Hep C RNA) test result at screening or within 3 months prior to
             first dose of study treatment, unless the participant can meet the following criteria:
             a. RNA test negative. b. Successful anti-viral treatment (usually 8 weeks duration) is
             required, followed by a negative hepatitis C virus (HCV) RNA test after a washout
             period of at least 4 weeks. - Intolerance or contraindications to anti-viral
             prophylaxis.

          -  Presence of active renal conditions (such as infection, severe renal impairment
             requiring dialysis or any other condition that could affect participant's safety).

          -  Ongoing Grade 2 peripheral neuropathy with pain within 14 days prior to randomization
             or ≥Grade 3 peripheral neuropathy.

          -  Active or history of venous and arterial thromboembolism within the past 3 months.

          -  Contraindications to or unwilling to undergo protocol-required anti-thrombotic
             prophylaxis.

          -  Current corneal disease except for mild punctate keratopathy.

          -  Any serious and/or unstable pre-existing medical, psychiatric disorder or other
             conditions (including laboratory abnormalities) that could interfere with
             participant's safety, obtaining informed consent or compliance to the study
             procedures.

          -  Pregnant or lactating female.