Shifting their sound and image from solely aggressive, masculine hip hop to more diverse styles, BTS wanted to express the beauty and anxiousness of "youth" and settled on the title of "花樣年華" (Korean: 화양연화; Romanized: Hwayangyeonhwa), loosely interpreted to define "youth" as "the most beautiful moment in life." Their third EP, The Most Beautiful Moment in Life, Part 1 (March 2015), explored the growth and emotional agony of youth as well as its playful and uplifting sides. Fuse included it as the only Korean album on their list of the "27 Best Albums of 2015 So Far." The EP has sold over 415,000 copies to date. Its lead single "I Need U" was BTS' first top five hit in Korea and garnered BTS first ever music show win on SBS MTV's The Show. While its second single, "Dope (Korean: 쩔어; Romanized: Jjeoreo)", only peaked at number 44 in Korea, it peaked at number three on Billboard's World Digital Songs Chart and became their first music video to accrue over 100 million views on YouTube in October. The group began the world tour extension of their Red Bullet Tour in June, titled 2015 Live Trilogy Episode II: The Red Bullet, visiting cities throughout Asia, Oceania, North America, and Latin America. Their fourth Japanese single, "For You", was released on June 17 to celebrate the first anniversary of their Japanese debut and topped Oricon's daily chart, selling over 42,000 copies within its first day. BTS later performed at Japan's Summer Sonic Festival on August 15 and 16.
In November, BTS commenced their third concert tour, 2015 BTS LIVE "The Most Beautiful Moment in Life: On Stage", debuting their new song and the lead single from their fourth EP The Most Beautiful Moment in Life, Part 2, "Run", during the Seoul dates. Thematically, the EP focused more on the serious and speculative aspects of youth, touching on the pursuit of success, loneliness, affection for their origins, and the suffering of the younger generation due to unfavorable conditions in current society. Critically, it was praised as the successful merging of the style of The Most Beautiful Moment in Life, Part 1 with BTS' initial identity. The album topped the weekly Gaon Album and Billboard World Albums charts and BTS became the first K-pop act to remain atop the latter for multiple weeks. It also marked their first appearance on the Billboard 200 chart, peaking at number 171 with over 5,000 copies. BTS were awarded Best World Performer at the 17th Mnet Asian Music Awards in recognition of their international fan base.
Their first Korean compilation album and the finale to their "youth series", The Most Beautiful Moment in Life: Young Forever, was released in May 2016. It included three new singles: the top 40 hit "Epilogue: Young Forever", the top 10 hit "Fire" (Korean: 불타오르네; Romanized: Bultaoreune), and the top 20 hit "Save Me". The album topped Gaon Weekly Chart in Korea for two consecutive weeks and peaked at number 107 on the U.S. Billboard 200. The Most Beautiful Moment in Life: Young Forever later won BTS' first major Korean award for Album of the Year at the 8th Melon Music Awards. BTS embarked on their Asia tour extension, 2016 BTS LIVE "The Most Beautiful Moment in Life On Stage: Epilogue", from May to August, visiting 10 cities and performing to 144,000 fans. During their tour, BTS held a landmark two-day concert at the Olympic Gymnastics Arena in Seoul in May, and performed as first time headliners at both U.S. KCON shows held that year in Newark (June) and Los Angeles (July), to sold-out audiences. In line with their other successes, they became the first K-pop group to receive their own Twitter emoji in May 2016.
In September 2016, BTS released their second Japanese studio album Youth. It sold over 44,000 copies on its first day of release and peaked at number one in Japan. Pre-orders for their second Korean studio album Wings, released in October 2016, accumulated over 500,000 copies within the first week. Wings combined the themes of youth presented in their previous "youth series" with temptation and adversity and, for the first time as a major group effort, included seven solo tracks that demonstrated each members' potential and individuality as independent musicians. The album was generally well-received by critics, with Rolling Stone naming it "one of the most conceptually and sonically ambitious pop albums of 2016," while Fuse praised the "vulnerable and honest song material" and diverse tracks. The lead single "Blood Sweat & Tears" achieved a music chart "all-kill" in South Korea and became their first number one hit on the weekly Gaon Digital Chart. Its music video gained over 6 million views within 24 hours, breaking the previous record held on YouTube for the highest number of views of a K-pop group music video within 24 hours. Wings opened at number 26 on the U.S. Billboard 200, the highest chart ranking ever for a K-pop album, and BTS became the first Korean group to top the Billboard Social 50 chart that month. It was their first "million seller" album, moving over 1.5 million copies in South Korea that year and became the best-selling album in Gaon Album Chart history at the time. BTS were the first artist not from a "Big Three" entertainment company (SM, YG and JYP) to win Artist of the Year at the 18th Mnet Asian Music Awards in December.