The away goals rule - which saw goals scored away from home worth double should a two-legged tie end level - had been in place since 1965 and will now be replaced by extra-time and penalties.
European football's governing body have presented stats detailing a decline in home advantage since the mid-1970s, while president Aleksander Ceferin said the away goals rule dissuades home teams from playing attacking football.
Ceferin said: "The away goals rule has been an intrinsic part of Uefa competitions since it was introduced in 1965.
"However, the question of its abolition has been debated at various Uefa meetings over the last few years. Although there was no unanimity of views, many coaches, fans and other football stakeholders have questioned its fairness and have expressed a preference for the rule to be abolished.
"The impact of the rule now runs counter to its original purpose as, in fact, it now dissuades home teams - especially in first legs - from attacking, because they fear conceding a goal that would give their opponents a crucial advantage.
"There is also criticism of the unfairness, especially in extra-time, of obliging the home team to score twice when the away team has scored.
"It is fair to say that home advantage is nowadays no longer as significant as it once was."
Uefa cited higher-quality and standardised pitches, technology such as goal line and VAR, "higher security conditions" and more sophisticated TV coverage as factors that have caused a blurring of the "lines between playing at home and away".