"Wonderful being in Seoul. My gratitude to the Indian community here for the very warm welcome," the prime minister tweeted.
Indian community members in large number, waving small tri-colour flags, were at the ROK Airbase to welcome the prime minister, who arrived from Ulan Bator.
"Immense enthusiasm as PM @narendramodi reaches South Korea," the Prime Minister's Office tweeted with a picture of Indian diaspora members enthusiastically greeting the prime minister.
"Indian community welcomes PM @narendramodi to South Korea," the PMO tweeted.
"Annyeonghaseyo to the land of the morning calm! PM @narendramodi arrives in Seoul," External Affairs Ministry spokesperson Vikas Swarup tweeted.
Modi arrived in South Korea from Mongolia on a two-day visit.
After his arrival in Seoul, Modi went to lay a wreath at the Seoul National Cemetery.
He is set to attend a reception by the Indian community, during which 1,500 members will be present.
Later, he will be accorded an official welcome after which he will hold talks with President Park Geun-hye. A number of agreements are to be inked. Both leaders will make press statements.
President Park will host a banquet in honour of the Indian prime minister in the evening.