Election officials said the turnout was about 39%, compared to 60% in February polls.
The opposition had called for the boycott, saying new rules favoured pro-government candidates, who now dominate the 50-seat chamber.
The result also saw minority Shia MPs win their biggest tally, at 15.
Shia form 30% of the 1.2 million population and had seven candidates in February’s assembly, which was later dissolved by the Constitutional Court.
Three women were also elected to the new parliament, the National Election Commission said.
Islamists, liberals and Bedouins were among the main groups refusing to take part in Saturday’s election.
The opposition boycott means 60% of the assembly are new MPs.
The biggest change is for Sunni Islamists. The boycott reduced their representation from 23 to four.
Kuwait has seen months of confrontations between the opposition and government
The opposition said the new assembly was “unconstitutional”.
The Popular Committee for Boycotting the Election said the new body “does not represent the majority of Kuwaiti people and has lost popular and political legitimacy”.
It said any legislation would be illegal.