A once-daily 'closed' triple FDC therapy of FF/UMEC/VI via a single ELLIPTA® dry powder inhaler (DPI) is being developed by GlaxoSmithKline (GSK) with the aim of providing a new treatment option for the management of asthma by improving lung function, health-related quality of life (HRQoL) and symptom control over established combination therapies. This is a phase III, multi-center, active-controlled, double-blind, parallel-group study to compare the efficacy, safety and tolerability of the FDC of FF/UMEC/VI with the FDC of FF/VI. This study has 5 phases: Pre-Screening (Visit 0), Screening/Run-in, Enrolment/Stabilization, Randomization/Treatment, and Follow up. At Visit 1 (Screening), subjects meeting all protocol defined inclusion/exclusion criteria will enter a 3-week run-in period and will receive fixed dose inhaled corticosteroid/long-acting beta agonist (ICS/LABA) (fluticasone/salmeterol, 250/50 micrograms (mcg), via the DISKUS® DPI) one inhalation twice a day. At Visit 2 (Enrolment), eligible subjects will be enrolled into the 2-week stabilization period to receive FF/VI (100/25 mcg via the ELLIPTA DPI once a day, in the morning). At the conclusion of the stabilization period (Visit 3), all subjects who meet the pre-defined randomization criteria will be randomized 1:1:1:1:1:1 during the treatment period to receive either FF/UMEC/VI (100/62.5/25 mcg; 200/62.5/25 mcg; 100/31.25/25 mcg; 200/31.25/25 mcg) or FF/VI (100/25 mcg; 200/25 mcg) via the ELLIPTA DPI once daily in the morning. The duration of the treatment period is variable but will be a minimum of 24 weeks and a maximum of 52 weeks. Subjects will have up to 6 on-treatment clinic visits scheduled at Visits 3, 4, 5, 6, 7 and 8/End of Study (EOS) (Weeks 0, 4, 12, 24, 36 and 52, respectively). A follow-up visit will be conducted approximately 7 days after the end of treatment period or, if applicable, after the early withdrawal visit. Subjects will be provided with short acting albuterol/salbutamol to be used on an as-needed basis (rescue medication) throughout the study. Approximately 2250 subjects will be randomized, with approximately 375 subjects randomized to each of the 6 double-blind treatment arms to ensure approximately 337 evaluable subjects per treatment arm. DISKUS and ELLIPTA are registered trademarks of GSK groups of companies.