Harrison becomes the first to win multiple Olympic gold medals in the women's -78kg category and joins a short list of judokas who have won more than one gold in any weight class.
The 26-year-old American came out with all guns blazing and was clearly the aggressor the whole match but was only ahead by penalties with seconds to go, when she got Tcheumeo to submit on a hold for the match-ending ippon.
Rio 2016
Egyptian judoka sent home over handshake refusal with Israeli
15/08/2016 AT 19:51
The crowd was disappointed not to see a dream finals clash between Harrison and rival Mayra Aguiar of Brazil -- they had been shouting "Mayra is coming!" during the American's semi-final match with Slovenia's Anamari Velensek -- and boos rained down when Tcheumeo overcame Aguiar on penalties.
Aguiar and Velensek won bronze.
Rio 2016
Egyptian booed for not shaking hands with Israeli
12/08/2016 AT 17:55
Rio 2016
Baker wins -90kg men's judo in golden day for Japan
10/08/2016 AT 21:35