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Matthew Rees of Wales stopped 300 metres from the end to help Englishman David Wyeth, who was struggling with exhaustion, over the line.
"It'll be great to see David again - in happier circumstances," said Rees.
The pair will compete in the 10k event, which is broadcast live on BBC One, on Sunday, 28 May.
The two men had never met before April's London Marathon, but have communicated regularly since Rees generously stopped for Wyeth, who is from Manchester.
The pair eventually finished in two hours 52 minutes 26 seconds - with Rees losing scores of places in the race running order to come 986 in the men's overall.
Rees said he was just lending a hand to a "guy in need", but his actions drew praise from the Duke and Duchess of Cambridge and Prince Harry, race officials and many social media users.
Two amateur runners who provided the defining image of this year's London Marathon will be reunited at the upcoming Great Manchester Run.