Steve Agnew's side knew that a defeat at Stamford Bridge would result in their return to the Championship after just one season in the top flight and they proved unable to avoid that fate, marking the fourth time they have been demoted from the Premier League.
First-half goals from Diego Costa and Marcos Alonso left Middlesbrough with a huge task and there was to be no miraculous fightback, Nemanja Matic extending the league leaders' advantage after the break.
Boro join north-east neighbours Sunderland in the second tier despite making a decent start to the season following promotion under Aitor Karanka.
4 – No side has been relegated from the Premier League on more occasions than Middlesbrough. Tumble. pic.twitter.com/qONF43I56K— OptaJoe (@OptaJoe) May 8, 2017
Their home form was also poor, although they won three out of five matches at the Riverside Stadium ahead of the Christmas period, a run of form that appeared to signal an upturn in the club's fortunes.
But scoring goals was a problem for Boro all season and a 1-0 loss at Burnley on Boxing Day started a sequence of 12 matches in which they found the net just four times.
Karanka was unhappy at the club's transfer dealings in the January window and his departure finally arrived, via mutual consent, on March 16, with Boro three points from safety and having lost in the quarter-finals of the FA Cup to Manchester City.
Agnew took the reins but was unable to mount a recovery. Boro could only beat Sunderland in his nine matches in charge, with relegation back to the Championship confirmed on Monday.