Maatsen moves on a season-long loan deal.
The full-back has been capped up to Under-19 level for the Netherlands.
Manager Mark Robins said: “We're delighted to welcome Ian to the Club and would like to thank Chelsea for agreeing to loan him to us, and in particular Neil Bath.
“He is a very exciting player, who is good in possession and has great energy going forward too, and he will fit in well with the way that we play at Coventry City.
“We look forward to working with Ian this season."
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