Youngster has a chance to prove himself in one of Europe's top leagues
Queirós will wear the number 25 shirt this season for Effzeh and is set to link up with his team-mates and new boss Peter Stöger at their second training camp in Kitzbühel.
The 19-year-old centre-back arrives having made just the one appearance for the Ledman Liga Pro side when he played a full 90 minutes against Sporting Lisbon B in May.
Queirós has more experience at international level however, having played every minute during Portugal's run in the U19 European Championships in Georgia in July in which they reached the final, only to lose to England.
Köln delighted to secure a "great talent" in defence
Köln's managing director Jörg Schmadtke told the club's official website that Queirós "is a great talent" and added that the 19-year-old "complements our squad in the defensive area."
Schmadtke said that he feels Queirós can take "the next step in his development" with Effzeh and he "will make it into the Bundesliga" now that he has "the help of our coaching team".
Queirós also spoke following the announcement of his move, saying that he is "happy with the chance to play at 1. FC Köln" and is now "looking forward to the challenge" in the Bundesliga.
The club will take part in the UEFA Europa League this season following their fifth placed finish in last season's Bundesliga without last season's top scorer Anthony Modeste, who completed a loan move to Fabio Cannavaro's Chinese Super League side Tianjin Quanjian F.C. last week.