Jake Daniels has told Blackpool team-mate Marvin Ekpiteta that historical homophobic social media posts he made do not "define the man you are today".
Daniels is the first male professional in the UK for more than 30 years to come out as gay while still playing.
Ekpiteta, 26, then apologised for posts he called "offensive and completely inappropriate" from 2012 and 2013.
"I am proud to be your team-mate and to be part of the Blackpool family," Daniels, 17, said on social media.
"What you said 10 years ago at 17 years old doesn't define the man you are today. We are all moving football forwards together."
Daniels replied directly to Ekpiteta's apology on social media, in which he said: "I take full responsibility for these posts, and I am sorry."
Ekpiteta has since deleted the historical posts, which he said had been "highlighted" on Tuesday.
He played in the same Blackpool team as Daniels when the midfielder, who has been with the Seasiders since the age of seven, made his first-team debut on 7 May in defeat by Peterborough.
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"I want to wholeheartedly apologise for the offensive and completely inappropriate language I used, and for the sentiments I expressed," said Ekpiteta.
"As a footballer, and in the years spent in work, before I became a professional player, I've been fortunate to have worked with a wide and diverse range of people. Throughout this period, I have developed and grown as a person.
"Yesterday, I was proud of Jake and all involved at Blackpool FC for what is a hugely positive moment for football as a whole.
"I am embarrassed by the comments I made as a 17-year-old, nearly a decade ago, which do not in any way reflect the values I hold now or the beliefs I have as a person or as a team-mate.
"Football needs to be a place where everyone can feel free to be true to themselves, and I am upset that the comments I previously made suggest otherwise."
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