Yems, 63, was charged by the Football Association after he made 16 alleged comments which "included a reference to ethnic origin and/or colour and/or race and/or nationality and/or religion or belief and/or gender" to Crawley players between 2019 and 2022.
On Friday, the FA said Yems admitted one of the charges and denied 15. At a subsequent hearing, an independent Regulatory Commission found 11 of the alleged comments to be proven and four unproven.
In addition to his suspension, Yems has been ordered to attend an education programme.
A statement from the FA read: "An independent Regulatory Commission has suspended John Yems from all football and football-related activity up to and including 1 June 2024, and ordered him to attend an education programme for 12 breaches of FA Rule E3.2.
"The former manager of Crawley Town FC was charged with 16 alleged comments in breach of FA Rule E3.2 during the period between 2019 and 2022.
"It was alleged that each breach amounts to an 'aggravated breach' of FA Rule E3.2 as the comments included a reference to ethnic origin and/or colour and/or race and/or nationality and/or religion or belief and/or gender.
"It was further alleged that he had discriminated against Crawley Town FC players by reasons of ethnic origin and/or colour and/or race and/or nationality and/or religion or belief in breach of FA Rule E4 during the period between 2019 and 2022. However, this charge was denied by John Yems and later withdrawn by The FA prior to any hearing.
"Jon (sic) Yems admitted one of the remaining 16 charges and denied 15. An independent Regulatory Commission subsequently found 11 of them to be proven and four unproven during a hearing.
"The Commission also imposed his sanctions, and its written reasons for these decisions will be published at the earliest opportunity."
Yems, who took charge of Crawley in December 2019, was suspended for 12 days prior to his dismissal in May.
A number of players from the League Two club took grievances to the PFA, which sparked the investigations. And, on Friday, the PFA welcomed Yems' ban.
Former Nottingham Forest striker Jason Lee, who is now the Senior Equalities Education Executive for the PFA, said: "It takes bravery to come forward to report issues like this.
"When players make that decision, they are likely to have given it a lot of thought. 'What will it mean for my future at the club? Will it impact my career if I say something?'
"One of the most significant considerations will be the risk that they will be ignored or that they won't be taken seriously.
"It's a massive thing for any individual to do, and that's why it's so vital that players have confidence that they will be listened to, believed and supported.
"This case has taken time, but the fact that it was taken all the way through to today's conclusion is vital.
"The FA have also demonstrated the seriousness with which they take this, and they should be commended for making sure the process was followed. It shows that a collaborative effort on these issues can achieve positive outcomes."