The design of the team's third kit, which can be worn as an alternative to the home or away kits, makes reference to the 50th anniversary of the club's first European Cup Final success over Benfica in May 1968.
The navy blue shirt takes its colour from the royal blue kit worn by the team in the historic game. The shirt also pays homage to the cup final victory with gold detailing on the adidas logo and club crest.
It shows its support for Parley with the words "For the Oceans" printed along the inner neckline.
"It's great to be able to celebrate the 50th anniversary of the Club's first European Cup win," said United director Richard Arnold.
"This jersey represents an important moment for our club, and combines our record-breaking history – when we became the first English team to win the competition."
"We are all acutely aware of the threat of plastic to the environment and we are delighted to be able to raise further awareness with this recycled kit, which I am sure the fans will love," continued Arnold.
Adidas supports Parley in both its education and communication programmes, and its ocean plastic program, which is dedicated to ending plastic pollution in our oceans. The sportswear brand has committed to using recycled plastic in all its products by 2024.
Adidas previously partnered with Parley to update one of its classic shoes from the 1990s – the EQT Support ADV sneaker – with yarns made from up-cycled plastic waste collected from beaches and coastal communities in the Maldives.
The long-standing collaboration also saw the two organisations release a collection of swimwear made from up-cycled fishing nets and debris in coastal areas.
"We all need to change the way we think and act towards our oceans. It is this core belief that we all share at adidas, which is the reason why our innovative partnership with Parley for the Oceans is so important to us," said Adidas product director Oliver Nicklisch.
"By working with Manchester United to create new, stunning jerseys made with Parley Ocean Plastic, we hope that we can highlight the issue of plastic damaging our oceans, and ultimately encourage and inspire football fans to join us in creating a better environment for everyone," he continued.
The third kit became available on 11 May 2018, and will be worn on pitch for the first time during United’s pre-season summer tour in the USA.
This isn't the first football kit Adidas has released with Parley. In 2016 Adidas created shirts from ocean plastic for the Real Madrid and Bayern Munich teams to be used in one-off matches.
Major League Soccer also joined Adidas and Parley earlier this year to promote the health of our oceans, as Parley jerseys were worn by all Major League Soccer teams playing over the Earth Day weekend, from 20 to 22 April 2018.