United had led through Billy Sharp and a Rodolph Austin wonder goal but were unable to maintain their frenetic pace and were duly unpicked by Slavisa Jokanovic’s dangerous side.
The automatic promotion hopefuls pulled one back before half-time thanks to a clinical Troy Deeney finish and then a double from Matej Vydra sealed the turnaround to put them a point off the top.
It was perhaps a little harsh on Leeds, who had enough chances to win two games, but their inability to deal with the blistering movement of Deeney and Vydra cost them.
Leeds had won five out of six prior to their midweek loss at Brighton and started with the clear intention of embarking on another run.
Watford helped them on their way to a seventh-minute lead, though, with Ikechi Anya and Heurelho Gomes getting involved in a horror mix-up.
The latter tried to head Luke Murphy’s off-target pass to the former but was far too heavy with his touch, forcing the ex-Spurs man to make an unexpected save. He could push it no more than a couple of yards, though, and found Sharp waiting to slam in the 150th goal of his career from close range.
It got better for Leeds 12 minutes later with a goal as impressive as the first was fortunate. Austin took the ball in 20 yards from goal in the right channel, controlled it with his thigh and then dipped an exceptional volley over a helpless Gomes.
Watford were shell-shocked and locked out of the game, although they nearly got back into it when Sol Bamba accidentally bundled the rebound of a Juan Carlos Paredes shot towards his own goal, only for keeper Marco Silvestri to snaffle it.
But they got themselves back into it six minutes before the break through Deeney’s 14th goal of the season. The striker ran on to Vydra’s long ball and was too quick for Bamba and Scott Wootton, slotting comfortably beyond Silvestri.
Bamba redeemed himself shortly after, though, blocking Vydra on the line as he prepared to celebrate tapping in a Deeney cross.
Leeds were creaking but Austin could have settled them 20 seconds after the break. Sharp sent him clear but he hit at Gomes, with a weak follow-up cleared off the line by Gabrielle Angella. Austin then teed-up Sharp but he missed his kick at the front post.
Watford made sure they made the most of their good fortune, levelling on 56 minutes. A flowing move, involving fine control from Almen Abdi, ended up with Deeney and, clean through, he squared for Vydra who did the rest.
The Hornets were buzzing and Vydra should have scored a minute later but hit at Silvestri when through, although he did get the winner with 10 minutes left.
It came from a Leeds attack, Murphy beating three men to get in the box before losing possession. From there the ball got to Deeney on the right, he went long to Vydra and, although his first shot was saved, he beat Bamba to the rebound and put it in.