The 2019 season marked the most successful one in the club's footballing history. At the end of 2018, Rodolfo Landim was elected club president for a three-year term. Flamengo paid the most expensive incoming transfer fee for a player in Brazilian football history, signing Giorgian de Arrascaeta from Cruzeiro for R$63 million (€14.5 million). In January the club signed forward Bruno Henrique from Santos and secured the loan of striker Gabriel Barbosa from Inter Milan.

After advancing out of the Copa Libertadores group stage, manager Abel Braga resigned and Flamengo hired Portuguese manager Jorge Jesus. Europe-based players Rafinha, Filipe Luís, Pablo Marí and Gerson were added to play alongside Flamengo's other record signings. After qualifying to their first Copa Libertadores semi-final since 1984, Flamengo defeated Grêmio   5-0 in their home leg at the Maracanã to advance their first Copa Libertadores final since 1981. For the first time in Copa Libertadores history, the final was played as a single match in a neutral venue. On 23 November 2019, at the Estadio Monumental in Lima, Peru against defending champions River Plate, Flamengo trailed 0–1 in the final minutes before Gabriel scored twice to secure the 2–1 victory.

Less than 24 hours later, Flamengo became champions of the Campeonato Brasileiro Série A for the first time since 2009 with four matches in hand after a loss by Palmeiras to Grêmio in the 34th round. Flamengo became only the second Brazilian club to win their state championship (2019 Campeonato Carioca), Campeonato Brasileiro, and Copa Libertadores in the same season, after Pelé's 1962 Santos team. Flamengo's 2019 campaign under Jorge Jesus' leadership broke a number of records in the Campeonato Brasileiro's 20-team double round-robin era (2006–present): most points (90), most wins (28), most goals scored (86), best goal differential (+49), longest undefeated streak (24 matches), most points clear of runners-up (16) and most goals by a single player (25 from Gabriel Barbosa).