AirHint found the following cheapest return flights from Seattle (SEA) to Rome (FCO) in September 2025 (see full year).

Return flights

10 Sep - 26 Sep	Aer Lingus
18 Sep - 22 Sep	Icelandair
10 Sep - 17 Sep	United
23 Sep - 07 Oct	Aer Lingus
16 Sep - 23 Sep	United
03 Sep - 12 Sep	United
23 Sep - 15 Oct	Condor
02 Sep - 14 Sep	Icelandair
01 Sep - 16 Sep	Icelandair
08 Sep - 17 Sep	Condor
11 Sep - 29 Sep	Condor
07 Sep - 14 Sep	United
28 Sep - 05 Oct	United
21 Sep - 04 Oct	Air Canada
25 Sep - 02 Oct	United

Also check the deals for one-way flights from Seattle to Rome in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Seattle to Rome in September from 471€

Return flights