Vasyl Lomachenko became only the 12th boxer in Olympic history to win two titles with a comprehensive win over Han Soon-chul in the lightweight final.
The 24-year from Ukraine was a class above the South Korean and won 19-9.
Lomachenko, who never looked in danger of losing the bout, adds the lightweight title to the flyweight crown he won in Beijing four years ago.
The flyweight division has been scrapped in these Games but the change in weight did not faze Lomachenko.
The Ukrainian, regarded by some as the world's best amateur, has excelled at the higher division and went into the final at the ExCeL as the number one seed.
He dominated from the opening bell, negating Han's superior reach and height with his excellent footwork and hand speed to establish an early lead.
Han tried to get on the front foot in the second round but did not up his tempo sufficiently, and an efficient performance from Lomachenko extended his advantage to 11-5 before a third round that saw him add eight further points to conclusively seal the win.
Lomachenko won a tough fight 14-11 against Yasnier Toledo of Cuba in the semi-finals in what was a repeat of last year's World Championship final, while Han was awarded a questionable 18-12 verdict over Evaldas Petrauskas of Lithuania in his semi.
The Ukrainian was given the Val Barker Award in Beijing for the tournament's best boxer and, after making history at these Games, is a strong candidate to receive it for a second time.