Ralf Rangnick brought both squads together as the football community came together in protest against Russia's invasion of Ukraine.
The idea for both sets of players to come together came from the interim boss, United said.
The Red Devils weren't the only team to show solidarity for Ukraine, as fellow Premier League side Crystal Palace sent out their support as well.
A message on the big screen at Selhurst Park read: "We stand with Ukraine."
League Two side Bradford City also followed suit, with the club stating that a minute's applause will take place 30 minutes into their home match against Mansfield.
On Twitter, they wrote: "Half an hour into today's clash, the @UtilitaEnergy Stadium will #StandWithUkraine with a minute's applause - showing solidarity with our friends @Uki_Bantams."
Aston Villa right-back Matty Cash also revealed a message under his shirt after scoring against Brighton.
It said: "Thomasz Kedziora + family, stay strong my bro".
Kedziora is Cash's Poland teammate, who plays for Dynamo Kyiv and remains in the Ukrainian capital.
The Villa defender also wrote a message on Twitter before the game after Poland announced they will refuse to face Russia in next month's World Cup play-off.
"We, the players of the Polish national team, together with the Polish Football Association, decided that as a result of Russia's aggression against Ukraine, we do not intend to play in the play-off match against Russia," his statement read, along with the flags of Poland and Ukraine either side of a handshake emoji.
"It is not an easy decision, but there are more important things in life than football.
"Our thoughts are with the Ukrainian nation and our friend from the national team, Tomasz Kedziora, who is stil in Kiev with his family."
Elsewhere in sport, the 2022 Champions League final has been moved by UEFA from St Petersburg to Paris and Formula 1 have confirmed that the Grand Prix in Sochi on September 25 has been cancelled.