He won his first Grand Prix in 1994 by knocking out Rob van Esdonk and Patrick Smith in the quarter-finals and semi-finals, respectively, before taking a unanimous decision over Masaaki Satake in the finals.

[7] On 18 November 1991, Aerts defeated the legendary Frank Lobman via unanimous decision in Rotterdam to win the WMTA World Heavyweight Muay Thai Championship.

On January 29, 1993, Aerts defeated Peter Selkthorpe of England by first-round knockout with a knee strike to win the European Muay Thai title in Best, Netherlands.

[9] Fifteen days later in Amsterdam, Aerts made the first defence of his WMTA World Heavyweight Muay Thai Championship against Rob van Esdonk, knocking him out with a right hook less than a minute into round four.

Aerts knocked out Markus Fuckner of Germany on February 20, 1994, in Amsterdam to retain the WMTA Heavyweight Muay Thai title before heading out to Japan to take part in the K-1 Grand Prix '94 which was held in Tokyo on April 30, 1994.

Aerts then made the third defence of his WMTA World Heavyweight Muay Thai title against Ergin Solmaz in Amsterdam on November 12, 1994, before going back to Japan to fight Glen Parker at K-1 Legend.

The fight did not last long, as Aerts finished Le Banner with a body shot in round one to become the K-1 World Grand Prix Champion for the second year running.

[14] He ended the year with a forty-second KO win over Mike Bernardo, the hard hitting South African known for his punching power, at K-1 Hercules on December 9, 1995.

Already a dominant name in K-1 and the reigning Grand Prix champion, Aerts was the favorite to win the 1996 tournament and as he had demolished Bernardo just six months earlier, he was expected to do the same this time.

He returned to the ring for the first time since his trilogy with Mike Bernardo on March 16, 1997, at K-1 Kings '97 where he had the first of his four meetings with legendary Swiss Kyokushin fighter Andy Hug.

Peter Aerts began 1999 in a rich vein of form, finishing Michael McDonald, Jim Mullen, Matt Skelton, Maurice Smith and Sam Greco, respectively, over the course of five months.

Although dazed and clearly hurt, Le Banner was able to make the count and came back to knock Aerts out with a devastating left hook at just over the one minute-mark of round number one, sending the reigning champion crashing out of the tournament.

[40] After a decision loss to Mirko Cro Cop at K-1 Gladiators 2001[41] and a TKO win over Nobu Hayashi at K-1 Burning 2001[42] in early 2001, he entered the K-1 World Grand Prix 2001 in Las Vegas on August 11, 2001.

[44] He kicked off 2002 with wins over Nicholas Pettas and Andrei Kirsanov in the first half of the year before losing a majority decision to Alexey Ignashov at the K-1 World Grand Prix 2002 in Fukuoka on July 14, 2002.

And while Andy Hug died and other old-school legends Branko Cikatić, Mike Bernardo, Sam Greco, Ernesto Hoost and Stan Longinidis all retired, Aerts continued to face the new generation of stars.

[48] He rebounded from two consecutive defeats, however, and knocked out Tsuyoshi Nakasako with a high kick at K-1 Beast II 2003 on June 29, 2003[49] before qualifying for the 2003 K-1 WGP by beating Jerrel Venetiaan via unanimous decision (30-29, 30–29, 30–28) at K-1 World Grand Prix 2003 Final Elimination on October 11, 2003.

[54] After a relatively poor 2004, Aerts went into 2005 with an extra round unanimous decision (9.5-8, 10–8.5, 10–8) over American prospect Carter Williams in a superfight at the K-1 World Grand Prix 2005 in Seoul on March 19, 2005.

[57] Having made his debut in mixed martial arts on July 6, 2005, when he knocked out former sumo wrestler Wakashoyo at Hero's 2, Aerts returned for his second and last MMA bout against judoka Shungo Oyama at K-1 PREMIUM 2005 Dynamite!!

He defeated Musashi by first-round KO, and after Remy Bonjasky was forced to withdraw from the Grand Prix due to an injury, Aerts took his place and met Glaube Feitosa in the semi-finals.

After knocking the karate man down with a barrage of strikes in round two, the referee stopped the fight and Aerts went through to the final where a rematch with reigning champion Semmy Schilt awaited.

After a quick knockout of Junichi Sawayashiki in the quarter-finals, he met two-time K-1 World Grand Prix winner Remy Bonjasky in the semis and dominated him en route to a unanimous decision (30-29, 30–27, 30–28) win which would take him into the final for a rubber match with defending champion Sem Schilt.

[76] Following this defeat, Aerts regained some of the weight that he had lost for his match against dreadlocked karate man Ewerton Teixeira at the K-1 World Grand Prix 2010 in Seoul Final 16 on 2 October 2010.

[81] After that fight, Aerts signed a contract to compete exclusively for at least the next two years with GLORY, a newly formed kickboxing league which numerous top champions joined following the demise of K-1.

[87][88][89] In what was publicized as his retirement match, Aerts lost a tightly contested split decision to Rico Verhoeven at Glory 13: Tokyo, Japan on 21 December 2013.

[103] In June 2015, Aerts – at 44 years old – officially announced his retirement via video at a press conference for an upcoming kickboxing show in Japan that he was scheduled to appear on.

[104] Aerts' retirement was short-lived, however, and he returned to the ring to compete in his third mixed martial arts match, against the debuting Estonian sumo wrestler Baruto Kaito at Rizin World Grand Prix 2015: Part 2 at the Saitama Super Arena on 31 December 2015.

Afterwards, he was joined in the ring by fellow Dutch kickboxing legends Ernesto Hoost, Remy Bonjaskyn and Semmy Schilt, who were on hand to congratulate the retiring Aerts.

[110][111] He defeated Christian Müller via KO due to a knee strike in the first round of their match at La Familia Fight Night X in Halle, Germany on 4 May 2019.

[112][113] The 49-year-old Aerts won against 45-year-old Brazilian-Japanese opponent Jairo Kusunoki via a low kick KO early in the second round at HEAT 46 in Tokyo on 19 January 2020.

[119] Aerts played a fictionalized version of himself in the 2011 Dutch comedy film New Kids Turbo in which the protagonists, a group of guys who always look for trouble and create chaos in a small village, borrow some money from him.