The 25-year-old scored 10 goals and provided five assists as he helped Everton avoid relegation last season. He scored 43 goals in 135 league appearances for the Toffees after joining from Watford in July 2018.
The Hornets had signed Richarlison for £11.5m from Brazilian side Fluminense in 2017.
Playing either as a wide attacker or central striker, Richarlison finished as Everton's joint-top scorer across all competitions in his opening two seasons on Merseyside, reaching double figures in three of the four seasons he spent with them. He made his senior international debut for Brazil in September 2018 as a second-half substitute in their 2-0 win over the United States and has gone on to make 36 appearances, scoring 14 goals.
In 2019, he was named in the 23-man squad for the Copa America and scored in the final as Brazil won the tournament for the first time since 2007.
He also played at the rescheduled 2020 Summer Olympics in Tokyo, finishing as the tournament's leading scorer with five goals as his side won gold.
Tottenham have brought in the forward as they prepare for a season in which they have qualified for the Champions League.
They have already signed England goalkeeper Fraser Forster on a free transfer after the 34-year-old left Southampton, as well as Croatian winger Ivan Perisic on a free transfer from Inter Milan and Brighton and Mali midfielder Yves Bissouma.
In a statement, Everton thanked Richarlison for his service and commitment during his time with the club.