The teenager produced a quality finish in the 24th minute to defeat QPR and deliver a first victory since beating Brentford in August.
It was only their second victory of the season but thoroughly deserved after a performance full of endeavour and character in caretaker manager Paul Warne’s second game in charge.
Indeed, the hosts should have won by a larger margin, the tireless forward Danny Ward - on his 26th birthday - hitting the crossbar with a fearsome strike in the second half and Joe Newell somehow skewing the rebound over.
As they chased what would have been a deserved second, they also had a chance cleared off the line, Anthony Forde fired another effort straight at Alex Smithies and Jon Taylor missed when Ward was unmarked and better positioned in the middle.
Inspirational captain Lee Frecklington, on his return from injury, led from the front, his combative quality in midfield crucial as QPR tried to get on top.
Elated, he charged over to embrace Warne once the final whistle sounded.
Keeper Lewis Price made a series of outstanding saves while Richard Wood was a rock at the back.
Aimen Belaid, unfancied by previous managers, made his first appearance in 11 months, the Tunisian faring well and making a vital tackle on Conor Washington as QPR pressed for the equaliser late on.
Rotherham showed their promise immediately when the returning Frecklington surged into the box onto Brown’s smart pass and drilled a shot that Smithies saved well after just 60 seconds.
Similarly, though, Price was soon forced into producing a spectacular stop as Washington curled a shot towards the top corner.
It was QPR who then enjoyed more of the play in the first half but Warne’s side were competitive, energetic and threatening themselves at times.
Ward’s header drifted just wide and Newell escaped down the left, too, but Ward could not reach his searching cross.
Brown made the breakthrough, the 19-year-old showing his obvious class with a lovely finish after combining well with Ward for his third goal in 16 games since joining.
At the start of the second period, Price continued his excellent form to deny Tjaronn Cherry’s dipping free-kick before another quality delivery from Newell saw Smithies desperately scrambling to deny Rotherham that second.
It was the home side, though, who got stronger and brought that much-needed win.
Rotherham United: Price; Fisher, Wood, Belaid, Mattock; Forde, Adeyemi (Vaulkes 85), Frecklington, Newell (Kelly 90); Brown (Taylor 85); Ward. Unused: Bilboe, Ball, Blackstock, Yates.
QPR: Smithies; Onuoha, Hall, Lynch, Bidwell; Sandro (Gladwin 72); Chery (Wszolek 89), Cousins, Luongo, Ngbakoto (Polter 59); Washington. Unused: Ingram, El Khayati, Henry, Shodipo.
Referee: J Simpson