The Belgium international moved to Manchester United in a £75m deal from Premier League rivals Everton in the 2017 summer transfer window.
Lukaku scored on his Manchester United debut in the Premier League with a goal in a 4-0 victory over West Ham United at Old Trafford.
Romelu started his professional career with Anderlecht before he completed a switch to Chelsea in 2011 under Andre Villas-Boas.
He went on loan to West Brom and Everton before Chelsea sold the striker to the Merseyside club in a £29m transfer in 2014.
Lukaku is Belgium’s all-time record goal-scorer after he netted his 31st international goal in a 1-0 victory over Japan in November 2017.
• Date of birth: 13 May 1993
• Age: 26 years old
• Place of birth: Antwerp, Belgium
• Nationality: Belgian
• Height: 190cm / 6ft 3ins
• Weight: 93.8kg / 207 lbs
Romelu began his football career at the age of five. He started at Rupel Bloom before he moved to Belgian Pro League club Lierse.
He scored 121 times in 68 games between the age of 11 and 13 to underline his promising potential at youth level.
Anderlecht raided Lierse in 2006 and Lukaku was one of 13 youngsters to move to the Belgian giants.
Lukaku continued his prolific record at youth level with 131 goals in 93 games with Anderlecht.
Unsurprisingly, the Belgian club were eager to tie down Lukaku to a professional contract. He signed a three-year deal in May 2009.
Romelu made his professional debut in a 1-0 loss to Standard Liege in May 2009. He scored his first goal as a late substitue to seal a 2-1 win for Anderlecht in August 2009.
Lukaku ended the 2009-10 season with an impressive return of 19 goals in 45 appearances in all competitions. He played a big role in helping Anderlecht to win the Belgian title.
He finished his second campaign with 20 goals in 46 games both domestically and in Europe but Anderlecht missed out on successive Pro League titles.
Chelsea agreed a £17m transfer deal with Anderlecht for Lukaku in August 2011. He signed a five-year deal and was handed the number 18 shirt.
Lukaku started his Chelsea career under Andre Villas-Boas. His first start came in Chelsea’s penalty shootout win against Fulham in the League Cup.
Romelu had to wait until 13 May 2012 under caretaker manager Roberto di Matteo to make his first Premier League start. Lukaku was named the man of the match after his assist for John Terry on his Blues debut.
Given a lack of opportunities at Chelsea, Lukaku moved to West Brom on a season-long loan at the start of the 2012-13 season in search of some vital Premier League experience.
Romelu scored on his West Brom debut after he netted their third goal in a 3-0 victory over Liverpool at the Hawthorns Stadium in the opening game of the campaign.
The Belgian striker scored on his first start for West Brom with the winner in a 1-0 victory over Reading. Ironically, Lukaku scored two goals in the same Premier League game for the first time with a double in a 2-0 victory at Reading.
Lukaku netted in the Baggies’ famous 2-0 win at Anfield to continue his prolific form. He secured a little slice of history with a hat-trick in a 5-5 draw with Manchester United in Sir Alex Ferguson’s final game in charge.
Romelu finished the season with 17 times in 35 Premier League games, which was more goals than any of his Chelsea team-mates.
Romelu made a disappointing start to the 2013-14 season after he missed the decisive penalty in Chelsea’s penalty shootout loss to Bayern Munich in the Uefa Super Cup.
He was sent out on loan again for the season after Jose Mourinho failed to guarantee the Belgian striker regular first-team football.
Lukaku opted to move to Everton and scored the winning goal in a 3-2 win at West Ham on his Toffees debut.
He helped to inspire Everton to a 3-1 win against eventual champions Manchester City at Goodison Park. Lukaku scored twice in a 3-3 draw with Liverpool in his Merseyside derby.
Romelu continued his record of scoring in big games with a goal and an assist in a 3-0 victory over Arsenal at Goodison Park following a spell on the sidelines with an injury.
Lukaku scored 15 times in 31 games to help Everton finish with their best Premier League points tally – 72.
The Belgium international completed a permanent £28m move to Everton from Chelsea in July 2014. He became the club’s most-expensive signing of all-time.
Lukaku scored his first goal since his permanent deal against former club West Brom. Romelu’s first Everton hat-trick came in a 4-1 victory over Swiss club Young Boys in the Europa League.
His second season at Goodison Park was a success with 20 goals in 48 games in all competitions.
Romelu started the 2015-16 season with a double in a 3-0 win at Southampton in their season opener. He continued his record of scoring against ex-club West Brom to help Everton make a solid start.
Lukaku scored in a 1-1 draw with Brendan Rodgers’ Liverpool team in October 2015 to build upon a prolific start to the campaign.
His brace in a 4-0 win against Aston Villa meant Lukaku became the fifth player under 23 years of age to score at least 50 Premier League goals. Other illustious names on the list include Robbie Fowler, Michael Owen, Wayne Rooney and Cristiano Ronaldo.
Romelu hit another milestone with his 50th goal in 100 appearances for Everton with the winner in a 1-0 victory over Crystal Palace in December 2015.
He finished the 2015-16 season with a career best 18 goals in 37 games. Lukaku was linked with a move in the 2016 summer transfer window given his prolific form for the Toffees.
Lukaku had a new Everton manager for the 2016-17 campaign following the appointment of Ronald Koeman as Roberto Martinez’s successor.
The Dutch coach managed to convince the striker to remain at Goodison Park.
He opened his account for the season with a hat-trick in a 3-0 win at Sunderland in September 2016. It was the twelfth fastest Premier League hat-trick after his three goals came in 11 minutes and 37 seconds.
He became Everton’s record goal-scorer in the Premier League when he netted in a 3-2 loss to Tottenham Hotspur at White Hart Lane. His 61st strike surpassed Duncan Ferguson’s tally of 60 Premier League goals.
The record continued to tumble when he became the first player since Bob Latchford to score 20 or more goals in three successive seasons for Everton.
Only Tottenham striker Harry Kane scored more goals than Lukaku in the Premier League in the 2016-17. The Spurs forward netted 25 goals in 36 games.
He was named in the PFA team of the year but missed out on the PFA young player of the year and player of the year awards.
Everton offered Lukaku £140,000 a week in March 2017 but the striker turned down the contract offer to open up the possibility of a summer move.
Lukaku was initially linked with a sensational return to Chelsea in the 2017 summer transfer window. However, Manchester United managed to beat their title rivals to the £75m deal plus £5m of add-ons to sign Lukaku.
Romelu was handed the number nine shirt after he signed a five-year deal with the 20-time English champions.
He scored on his Manchester United debut in a 2-1 loss to Real Madrid in the Uefa Super Cup.
Lukaku netted on his Premier League debut in a 4-0 win against West Ham in their season opener. He netted in five of their next six games in victories over Swansea City, Stoke City, Southampton, Crystal Palace and Everton.
Romelu’s first Champions League goal came in a 3-0 victory over Basel, before he netted twice in a 4-1 win at CSKA Moscow.
His nine goals in his opening 10 games in a Manchester United shirt broke Sir Bobby Charlton’s record.
Lukaku went through a dry spell between November and January.
However, he ended the campaign with a respectable 16 goals in 34 games in the Premier League.
Lukaku made his Belgium debut as a 16-year-old in 2010.
He scored his first international goals in a friendly against Russia.
Lukaku’s scored both of Belgium’s goals in a 2-1 win against Croatia to secure their place in the 2014 World Cup in Brazil.
He scored his first hat-trick for the Red Devils in a warm-up game against Luxembourg ahead of the major tournament.
Lukaku failed to score in Belgium’s 2-1 win against Algeria in their group-stage opener to be replaced by Divock Origi.
He scored his first World Cup goal in the 105th minute to secure a 2-1 win against United States in the round of 16.
His next big competition was Euro 2016. Lukaku scored twice in a 3-0 victory over the Republic of Ireland in the group stage.
Lukaku became Belgium’s record goal-scorer with the winner in a 1-0 victory over Japan. The Manchester United striker scored 34 times to break the record at just 24.
Lukaku was born in Antwerp to Congolese parents. The centre-forward decided to commit his international allegiances to his country of birth, Belgium.
His father Roger was a professional footballer. He represented Zaire at international level.
Romelu played alongside his younger brother Jordan at Anderlecht. His sibling is currently at Serie A giants Lazio.
• Romelu was a Chelsea fan during his childhood.
• He got to visit Stamford Bridge during his spell with the Anderlecht youth team. He said of Chelsea’s ground: “What a stadium. If one day in my life I will cry, it will be the day I play here. I love Chelsea.”
• Lukaku’s childhood idol was Chelsea legend Didier Drobga.
• Romelu is fluent in five languages: English, French, Dutch, Portuguese, Spanish and Congolese Swahilian dialect.
• Lukaku got permission from Manchester United striker Zlatan Ibrahimovic to take his number nine shirt.
• The Manchester United striker has got a Bachelor degree in tourism.
• Romelu has a passion for classic English cars. Bentley Continental GT Speed and Rolls-Royce Phantom Coupe.
MORE: Eden Hazard
MORE: The latest football news
MORE: The latest tennis news
BIOGRAPHY: Ethan Hazard
BIOGRAPHY: Daniel Sturridge