It is Suu Kyi's highest profile overseas visit since her pro-democracy party took power in April, ending nearly half a century of military domination.
Her government has seeded hopes for a new era of prosperity that could eventually convince the army of low-paid Myanmar labourers in Thailand to return home.
The two Southeast Asian neighbours have travelled in starkly different directions in recent years.
While Myanmar's junta has rolled back its chokehold on politics, last year allowing the freest elections in decades, Thailand remains in the grip of a military that seized power in 2014.
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The port, just outside Bangkok, is the seat of Thailand's huge seafood industry and home to more than 100,000 low-paid Myanmar labourers.
The visit "fills me with hope," Myanmar migrant Thon Barami, 50, told AFP at the scruffy port.
"We have problems here in Thailand. She might help us with labour rights... People all around the world will listen to her," she added.
The fishing sector has been battered by revelations of the use of slave labour and the widespread exploitation of workers.
Seeking to escape poverty at home, some one million registered Myanmar migrant workers form the backbone of Thailand's manual workforce.
Tens of thousands of others work illegally, with some estimates putting the total number of Myanmar nationals in Thailand at three million.
Rights groups say migrants -- legal and otherwise -- are vulnerable to unscrupulous officials, trafficking gangs and employment agencies who charge huge sums to get them poorly paid work.
Their low status also sees them treated with scorn and mistrust by many Thais.