Inclusion Criteria:  Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. At least 18 years of age, at the time of signing the informed consent. Diagnosed with Generalized Myasthenia Gravis (gMG) with confirmed documentation and supported by a physical exam and confirmed seropositivity for anti-acetylcholine receptor antibodies (AChR-Abs). Meets the clinical criteria as defined by the Myasthenia Gravis Foundation of America (MFGA) class II, III, or IV Has an Myasthenia Gravis - Activities of Daily Living (MG-ADL) total score ≥5 at screening and the day 1 visit, with more than 50% of the score due to nonocular symptoms Concomitant gMG treatment is permitted. Permitted concomitant gMG treatment includes nonsteroidal immunosuppressive drugs (NSIDs), steroids, and/or acetylcholinesterase (AChE) inhibitors. If receiving corticosteroids and/or NSIDs, must be on a stable dose for at least 1 month before screening.  Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies and:  a. Male participants:  Male participants are not allowed to donate sperm from signing the ICF until the end of the study.  b. Female participants:  Women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at baseline before investigational medicinal product (IMP) can be administered.  Exclusion Criteria:  Clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection at screening A positive test for SARS-CoV-2 at screening Any other known autoimmune disease that, in the opinion of the investigator, would interfere with an accurate assessment of the clinical symptoms of gMG and/or put the participant at undue risk  History of malignancy unless deemed cured by adequate treatment with no evidence of reoccurrence for ≥3 years before the first administration of the IMP. Participants with the following cancers can be included at any time, provided they are adequately treated at screening:  Basal cell or squamous cell skin cancer Carcinoma in situ of the cervix Carcinoma in situ of the breast Incidental histological finding of prostate cancer (TNM stage T1a or T1b) Clinical evidence of other significant serious diseases, a recent (<3 months) major surgery, or any other condition that, in the opinion of the investigator, could confound the results of the study or put the participant at undue risk A thymectomy within 3 months of screening Pregnant or lactating females and those who intend to become pregnant during the study or within 90 days of the last dose of IMP  Use of the following prior or concomitant therapies:  intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg) within 14 days of day 1 Rituximab within 6 months of day 1 Eculizumab within 1 month of day 1 Other monoclonal antibodies (eg, adalimumab, tocilizumab, ixekizumab) within 5 half-lives of the monoclonal antibodies before day 1 Use of any other investigational product within 3 months or 5 half-lives, whichever is longer, before day 1 Receipt of a live or live-attenuated vaccines received within 4 weeks of screening. The receipt of any inactivated, subunit, polysaccharide, conjugate vaccine at any time before screening is not considered exclusionary. Previous participation in a clinical study or patient access program during which they were treated with efgartigimod  Positive serum test at screening for an active viral infection with any of the following conditions:  Hepatitis B virus (HBV) that is indictive of an acute or chronic infection (https://www.cdc.gov/hepatitis/HBV/PDFs/SerologicChartv8.pdf) Hepatitis C virus (HCV) based on HCV antibody assay (unless associated with a negative HCV RNA test) HIV based on test results that are associated with an AIDS-defining condition or a CD4 count <200 cells/mm3 Total IgG <6 g/L at screening Known hypersensitivity reaction to efgartigimod or any of its excipients The participant stands in any relationship of dependency with the sponsor. The participant has been institutionalized due to an official or judicial order.