"I am sure all of us have been eagerly looking forward to this day for a long time!" Prime Minister Lee Hsien Loong wrote on Facebook.
"But please don't go overboard celebrating," Lee pleaded.
Local television reports showed a steady flow of customers as "non-essential" retailers opened for the first time in more than two months.
Singapore imposed a lockdown in April after a spike in novel coronavirus cases among migrant workers. The so-called "circuit breaker" ended on June 2, with some factories and offices reopening and flights permitted again to transit through the city-state's usually busy Changi Airport.
One hundred and forty-two new cases of the virus were confirmed by Singapore's Ministry of Health on Friday. The national total of 41,615 is the second-highest in South-East Asia, after the 43,803 diagnosed among Indonesia's 270 million people.
Home to 5.8 million people, Singapore has reported 26 deaths related to the novel coronavirus.
Most of Singapore's cases have been among roughly 323,000 male migrant workers who usually work in sectors such as construction but are confined to dormitories dotted around the city-state - living conditions that activists have slammed for fuelling the outbreak.
Friday's relaxations went ahead, the government said, "because community infection rates have generally remained stable, cases in migrant worker dormitories have declined, and there are no new large clusters emerging." - dpa