Larin took a weighted one-touch pass from Matias Perez-Garcia and put in his third goal of the season in the 73rd minute.
The Union nearly tied the score in the first minute of stoppage time, but Ilsinho sent a shot off the post and Joe Bendik made a save on Alejandro Bedoya.
Orlando City is 2-0-0. The Union is 0-1-2.
Larin gave Orlando City the lead in the 39th minute after converting a low cross from fellow striker Carlos Rivas. The Union thought Larin was offside, but defender Fabinho kept him on.
C.J. Sapong got his second goal in the 52nd minute to level the score with a header after Bedoya challenged a clearance and pressured the defense.
Orlando City played without Brazilian star Kaka because of a hamstring injury that will keep him out another month or so. Meanwhile, the Union was minus offseason signing Jay Simpson after he injured his ribs on March 11 vs. Toronto FC.
Giles Barnes, assuming Kaka's attacking role, missed a left-footed shot in the eighth minute, putting the ball just outside the right post. Barnes also had a free kick in the 27th that Andre Blake easily saved.
A few minutes earlier, the Union's Chris Pontius had a header from the left side of the box miss to the right as well.
The match was the second in Orlando City Stadium after the Lions defeated New York City FC in its christening on March 4
On April 1, Orlando City is at Columbus Crew SC and the Union hosts D.C. United.