Robert Kelley scored a touchdown on the opening drive before Giovani Bernard replied to tie the game.
Washington went in at half-time with a 10-7 lead, but Andy Dalton found Tyler Eifert in the end zone before he strolled in for a score himself in the third quarter.
Hopkins kicked a field goal to send the game to overtime, but neither side could find a game winning score in the additional 15 minutes.
Sides exchange touchdowns
Kirk Cousins picked up where he left off in Week 7, he was 3-for-3 on third down during the opening drive before Kelley's touchdown
However, the Bengals were immediately on the front foot after the next play, Alex Erikson returned the kick-off 65-yards, down to the Washington 36-yard line. Despite the Redskins having a lot of ball possession, Giovanni Bernard scampered into the end zone for an 8-yard score to tie the game.
The fast-paced opening quarter came to a close when Cousins found Pierre Garcon, who picked up yards after contact for a 23-yard gain. Cousins was able to move the ball around freely and in the space of two plays, he managed to gain 59-yards.
Redskins kick field goal for halftime advantage
Cousins found Vernon Davis for a 44-yard gain before the pair linked up once more the next play, but the Redskins were forced to kick a field-goal after being held out in the red zone.
Washington thought they had the ball back shortly after, but after Josh Norman stripped the ball out of Bernard’s arms, defensive holding was called. This didn’t come back to haunt the Redskins as Mike Nugent’s 51-yard attempt was no good.
Cousins tried to find DeSean Jackson midway through the next drive, but overcooked the throw, allowing George Iloka to intercept the pass. Washington could have gone into half-time with a six-point lead, but Hopkins’ 55-yard field goal attempt fell short and the remaining seconds ticked away.
Bengals score back-to-back touchdowns
Cincinnati came out and managed to go ahead on their first drive of the second-half; Dalton found Eifert in the end zone to put the Bengals ahead, but Nugent’s extra point missed.
The Redskins were made to pay for not taking advantage of their dominance in the first-half as the ‘home team’ extended their lead to 10-points.
Dalton drove his offense to the one-yard line, and faked the hand-off to Jeremy Hill, which allowed the quarterback to walk around in for the score.
Sides exchange scored in back and forth game
The Redskins replied on their next possession. Cousins found Jordan Reed, who cruised into the end zone for a 23-yard touchdown.
Will Compton picked off Dalton to set up the Redskins with good field position, on which they managed to capitalize. Then, Cousins fired the ball to a wide-open Jamison Crowder, who ran and dived for the end zone to put Washington back ahead in the game.
In a back and forth game, Dalton found A.J. Green on the next drive for a big gain before Hill ran into the end zone from 1-yard to put the Bengals back ahead.
Sides couldn't be separated in overtime
Just before the two-minute warning, Cousins found Jackson for a 14-yard gain to push the Redskins to midfield. And on 3rd-and-13, he found Crowder, who managed to avoid being brought down before getting past the first down marker.
Hopkins kicked a field goal to send the game to overtime, the first time a game in London has ever gone that far. But, the kicker missed a field goal in overtime, which would have won the game for the Redskins with minutes left on the clock.
Soon, time ran out as the two sides played out the first ever tied game in the International Series in London.