Hot favourite Andersson dominated the race and rarely looked troubled and had good lead as she strode into Stockholms stadion on Saturday afternoon 5:45 ahead of Aberash Tesfaye from Ethiopia.
Andersson became only the second runner to claim a trio of consecutive titles, joining Norwegian star Ingrid Kristiansen, who completed the feat in 1980-82.
Meanwhile, Lagat had the company of compatriot Hillary Kipchumba before he pulled away after the 30 kilometre mark. Kipchumba was beaten in to fourth by South African Johannes Kekana and compatriot Jonah Kibiwott Kemboi.
Lagat’s winning time of 2:12:48 was barely a minute off UK runner Hugh Jones’ course record of 2:11:37 from 1983. Lagat’s time will go down as the fourth-fastest.
The 32nd Stockholm marathon saw a record number of runners, with 20,136 registered boosted by a record number of female runners (4,695).