Ansarifard scored his third goal of the season
Nahki Wells' late penalty was saved by Costel Pantilimon as Nottingham Forest held on for victory at Queens Park Rangers.
Forest took what proved to be a decisive lead in the 55th minute when Joao Carvalho's through ball found Karim Ansarifard, who slotted past Joe Lumley.
The impressive Pantilimon twice denied Tomer Hemed and Massimo Luongo's spectacular volley flew just wide as QPR looked to respond.
But it was Wells who missed the hosts' best chance to salvage a point as the Bermudian striker saw his low penalty well saved by Pantilimon after Jack Robinson handled in the area.
Midfielder Joe Lolley could have added a second for Forest in stoppage time, but blazed over the bar.
Their victory was their first away from home in 15 games, and left them on course to secure a top-10 finish.
There were few chances in a quiet first half, with Lumley tipping Ansarifard's effort onto the woodwork and Pantilimon saving from Ebere Eze's long-range attempt.
And Wells' miss from the spot ensured QPR's dismal 2019, which has seen them win only twice, continued, leaving them 19th in the table.
Nottingham Forest manager Martin O'Neill said:
"QPR threw everything at us but I think the most clear-cut chances fell to us. The goal that we worked was terrific.
"I'm delighted to win the game, to win away from home for the first time for a long, long time, and it's back-to-back wins for us too - so all of those monkeys off our back.
"It was a great goal to win the game and we had to withstand a lot of pressure. They exerted a great deal of pressure on us but we withstood it and Pantilimon then makes a big save for us."
QPR caretaker-manager John Eustace said:
"That game summed our season up. We haven't been clinical enough. It's something we need to get right in the summer.
"It's important that we recruit winners - players who aren't used to losing. I think over the last two or three seasons the standards haven't been good enough and the recruitment is going to be massive this summer.
"We need to recruit hungry players who it means everything to them to win games. There were a lot of young players out there fighting for the club and the experience will only stand them in good stead for next year."
