US down Brazil to win CONCACAF Women's Gold Cup
US skipper Horan headed home in first-half injury time at San Diego's Snapdragon Stadium to settle a largely lacklustre finale to the 12-team tournament.
"I'm very very proud of the team right now," Horan said afterwards.
"We grinded out that win, again. It was a difficult game, Brazil challenged us in a different way.
"I'm really proud of us finding a way to get a goal and finishing out the game and getting a trophy."
Horan meanwhile said the US would take heart from the tournament victory as they build towards this summer's Olympics, noting the contributions of several younger players who have been drafted into the squad following last year's Women's World Cup last 16 exit.
"You see some of them playing in their first final tonight, and it was an amazing tournament for them," Horan said.
"Going into the Olympics we're going to see what they can do. I'm so proud because it looks like they're not young and inexperienced."
The Brazilians failed to register a single shot on target in the first half, with their best efforts a 10th minute free-kick from Dudi Sampaio that sailed over.
Gabi Nunes also saw a speculative 15th-minute strike from the edge of the area go soaring into the stands.
The American women were similarly off-target in the first half, struggling to create much in the way of goal-scoring opportunities from open play.
Horan had signalled her aerial threat in the 40th minute, stooping to direct a header that Brazil goalkeeper Luciana saved as it threatened to creep in.
At that stage, Horan's near-miss was the only US shot on target of the half.
But the breakthrough finally came on the stroke of half-time.
Trinity Rodman broke down the right flank before passing back to right-back Emily Fox in space.
Fox swung in an inviting deep cross to the back post and Horan was waiting to nod the header back across the goal to give Luciana no chance.
The second half continued in much the same vein, with both sides creating little of note.
US interim coach Twila Kilgore overhauled the US attack with a flurry of substitutions, bringing on Sophia Smith, Lynn Williams, Jaedyn Shaw and Midge Purce.
Those changes appeared to have delivered a second goal on 79 minutes when Williams pounced on a defensive mix-up to tuck away a confident finish.
But Williams had strayed just offside and the goal was chalked off.
Brazil triggered alarm bells in the US defence on 85 minutes when Geyse's clever flick from a free-kick floated just wide of Alyssa Naeher's post.
Debinha sent a Brazilian free-kick just over the bar in stoppage time, while at the other end, Luciana saved a Korbin Albert shot.