Inclusion Criteria:

          -  Acute myeloid leukemia (AML) according to World Health Organisation (WHO) 2016
             criteria and fulfilling all of the following criteria that defines "not candidates for
             intensive chemotherapy": (a) greater than or equal to (>=)75 years of age or (b)
             Comorbidity of at least one of the following: Eastern Cooperative Oncology Group
             (ECOG) Performance Status of 2; Severe cardiac comorbidity defined as congestive heart
             failure or ejection fraction less than or equal to (<=) 50 percent (%); Severe
             pulmonary comorbidity defined as documented pulmonary disease with lung diffusing
             capacity for carbon monoxide (DLCO) <=65% of expected, or forced expiratory volume in
             1 second (FEV1) <=65% of expected or dyspnea at rest requiring oxygen; Moderate
             hepatic impairment defined according to NCI organ dysfunction classification criteria
             (total bilirubin >=1.5 up to 3 times upper limit of normal [ULN]); Creatinine
             clearance <45 milliliter per minute per 1.73 meter square (mL/ min/1.73 m^2);
             Comorbidity that, in the Investigator's opinion, makes the participant unsuitable for
             intensive chemotherapy and must be documented and approved by the Sponsor before
             randomization; (c) De novo or secondary AML; (d) Previously untreated AML (except:
             emergency leukapheresis, 1 low dose of cytarabine and/or hydroxyurea during the
             screening phase to control hyperleukocytosis but must be discontinued at least one day
             prior to start of azacitidine). All trans retinoic acid (ATRA) treatment for presumed
             acute promyelocytic leukemia is permitted but must be discontinued at least 1 day
             prior to the start of azacitidine; (e) Not eligible for an allogeneic hematopoietic
             stem cell transplantation

          -  ECOG Performance Status score of 0, 1 or 2

        Exclusion Criteria:

          -  Acute promyelocytic leukemia with t (15;17), or its molecular equivalent
             (Promyelocytic leukemia [PML]-Retinoic acid receptor, alpha [RARalpha])

          -  Leukemic involvement or clinical symptoms of leukemic involvement of the central
             nervous system

          -  Use of immune suppressive agents for the past 4 weeks before the first administration
             of cusatuzumab on Cycle 1 Day 1. For regular use of systemic corticosteroids,
             participants may only be included if free of systemic corticosteroids for a minimum of
             5 days before the first administration of cusatuzumab

          -  Prior treatment with a hypomethylating agent for treatment of AML or myelodysplastic
             syndrome (MDS)

          -  A diagnosis of other malignancy that requires concurrent non surgical treatment

          -  Any active untreated systemic infection

          -  Known allergies, hypersensitivity, or intolerance to cusatuzumab or azacitidine or its
             excipients (that is, mannitol, an excipient of azacitidine)