The Barcelona forward, 28, passed Gabriel Batistuta`s 54-goal tally with a 25-yard strike.
Messi provided the assist for Ezequiel Lavezzi`s opener, then scored his stunner before Napoli`s Gonzalo Higuain fired in to make it 3-0.
Higuain scored with a tap-in in the 85th minute to complete the rout.
Find out how to get into football with our special guide.
"I am happy to have surpassed Batistuta`s record and I want to thank my team-mates, it`s theirs as well," said Messi, who turns 29 on Friday.
Hebei China Fortune winger Lavezzi will miss Sunday`s final, against Colombia or reigning champions Chile, because he fractured his left elbow after tumbling over the advertising boards.
The incident happened in the second half when the former Paris St-Germain player fell over backwards, trying to control a pass with his chest.
Lionel Messi breaks record as Argentina reach Copa America final
23 June 2016
Read: 1864
Lionel Messi became Argentina`s leading scorer with a superb free-kick as they beat hosts the USA 4-0 to reach Sunday`s Copa America final.
