"I am delighted to have joined Dinamo and I really want to make an impact here, primarily to help the club qualify for the Europa League group stage," Henriquez, who scored two goals in three international appearances, said on Monday.
"This is the right club for me at this stage of my career," added the 20-year old, who spent the last two seasons on loan at Wigan Athletic and Spanish side Zaragoza after joining United from Universidad de Chile in 2012.
Henriquez caught United's attention after scoring 21 goals in 17 games for Chile's Under-21 side, having also won two league titles and the Copa Sudamericana with Universidad, but has never got a look-in at Old Trafford.
He was an unused substitute in Wigan's shock 1-0 win over Manchester City in the 2013 FA Cup final.
Dinamo meet Romanian side Petrolul Ploiesti in the Europa League's two-legged playoff round.