Chanting slogans such as "we are boycotting", the demonstrators marched peacefully after the authorities issued a permit, in contrast to previous protests which have turned violent.
The opposition, comprising Islamists, nationalists and liberals, says the poll boycott is in protest at the government's unilateral amendment of the electoral law, which it describes as a violation of the constitution.
It claims the amendment, issued by Emir Sheikh Sabah al-Ahmad Al-Sabah in October, allows the government to influence the outcome of the results and elect a rubber stamp parliament.
No significant opposition figure is contesting Saturday's legislative polls and accordingly all 50 seats will be won by pro-government members.
Friday's protest was joined by large numbers of women, many of them veiled, as well as children carrying Kuwaiti flags and orange colour banners. Onlookers described it as one of the biggest ever in the oil-rich Gulf state.
"Absolute power corrupts" read a banner in English.
Enthusiastic crowds sang national songs and chanted slogans calling for a poll boycott as they wound their way through the streets, ending at the landmark Kuwait Towers on the seaside Arabian Gulf Road.
"I am here to protest against the law amendment because it is a breach of the constitution. It will elect a pro-government parliament," Abdullah al-Shemmari, a public sector engineer, told AFP.
Police were present in large numbers but in contrast to earlier protests which they have broken up violently, helped regulate traffic and ensured the march proceeded orderly.
Leading opposition figures and former MPs such as Ahmad al-Saadun, Mussallam al-Barrak and Faisal al-Muslim led the protest.
"Today, the Kuwaiti people are sending a message peacefully that we are against the amendment and against the oppressive attitude of the government," former MP Adel al-Damkhi said.
"The regime should read the message seriously that there is a real rejection of the law," Damkhi told AFP.
Under the previous law, Kuwaitis were able to vote for four of 10 MPs elected in each of the five constituencies, but the amendment saw this being reduced to only one.
The opposition claims that the reduction will encourage vote-buying and other corrupt practices since the number of votes needed to win a seat will be much lower than in previous polls.
The emir has said the amendment was within his constitutional rights and necessary to safeguard national unity and security of the oil-rich Gulf state.
Demonstrations held since October 21 have drawn tens of thousands of people, often turning violent when riot police used stun grenades and tear gas to disperse protesters. Around 150 protesters and 24 policemen have been wounded in the clashes.
The election is the second this year and the fifth since mid-2006 as the emirate is rocked by ongoing political crises between parliament and the government led by the ruling Al-Sabah family.