Half of 100 organisations polled by the Land Transport Authority (LTA) said they offer flexible work options to help their staff avoid the morning rush hour.
But fewer than one in 10 of their employees said they were aware of the schemes or had made use of them.
Minister of State for Transport Josephine Teo, who revealed the findings yesterday, said the feedback was "disturbing" and urged bosses to do more to encourage staff to change their travel habits.
"Besides family commitments that cannot be changed in the short term, the biggest impediment appears to be employer-related."
Mrs Teo was speaking at a seminar during which companies share their plans to help commuters beat peak-hour morning congestion.
It is part of the Government's pilot Travel Smart scheme to motivate staff to start their travel journeys earlier.
The scheme, which was launched last October, now has 12 companies committed to implementing flexi-work options such as staggering working hours, enabling employees to work remotely and even offering free breakfast to the early birds.
At Citi Singapore, it will soon be easier for employees to car-pool and share cabs with their colleagues, said human resources head Evangeline Chua.
The bank will also promote its shower and locker facilities for staff who choose alternative modes of transport such as cycling.
On the Government's part, it started offering free and discounted train rides last month.
Mrs Teo said the year-long trial has seen "some encouraging results", with more commuters catching a free train ride to the city area.
Current incentives such as a 50-cent discount for early travellers have reduced the number of peak commuters by 3 to 4 per cent.
Not good enough, said Mrs Teo. "Not everyone is able to but the number who can is potentially much bigger than those who have already shifted."
Citing a survey of public servants done last year, she said 35 per cent indicated that they would like to change their current work timings, with 7 per cent saying that they were willing to start work before 7.45am.
A retail leasing executive, who declined to be named, said she still clocks in at 8.30am and leaves only at 8pm. The 24-year-old added: "What is the point of flexi-work hours if our bosses expect us to stay till late?"
LTA senior manager Evan Gwee, who oversees the Travel Smart scheme, said bosses will have to "walk the talk" to change the work culture.
"They have to be open to the concept that workers can also be productive even if they are not at their desks, working the normal routine."