Police said there were five explosions caused by home-made devices in two areas of the capital Manama on Monday.
One of the men died at the scene when he kicked a device in Gudaibiya. The second died in hospital after being injured by an explosion near a cinema.
A third explosion in Adliya injured another man working as a cleaner. Officials said the victims were Asian.
Their nationalities are not known, but the biggest expatriate communities in Bahrain are Indian, Pakistani and Bangladeshi.
According to the 2010 census, there are more than 660,000 foreign nationals living in Bahrain – the vast majority of whom are described as Asian – out of a total population of 1,235,000.
The head of Capital Governorate Police urged all residents of Bahrain not to touch strange objects and to notify the authorities if they saw one.
An investigation into who caused the blasts, which the official Bahrain News Agency described as an "act of terrorism", is under way.
Last month, a policeman was killed by a bomb explosion while on patrol during an anti-government protest in the village of al-Akr. Another later died of burns he suffered after being hit by a Molotov cocktail in April.
Twitter sentences
Bahrain has been wracked by unrest since demonstrators took to the streets of Manama in February 2011, demanding more democracy and an end to what they said was discrimination against the majority Shia Muslim community by the Sunni royal family.
At least 60 people, including several police officers, have been killed, and thousands injured and jailed, since the uprising began in February 2011. The opposition puts the death toll at 80, a figure the authorities dispute.
Last week, the interior ministry announced a ban on all rallies and public gatherings, prompting condemnation from human rights groups.
Interior Minister Sheikh Rashid Al Khalifah said "repeated abuse" of the rights to freedom of speech and expression could no longer be accepted.
UN Secretary General Ban Ki-moon said the ban "could aggravate the situation in the country" and urged the government "to lift them without delay", while the US State Department said it was "deeply concerned".
On Wednesday, foreign ministers from the Gulf Co-operation Council are scheduled to meet in Bahrain to discuss regional issues, including the unrest in Bahrain and Kuwait, where opposition supporters have been protesting against the emir’s changes to the electoral law.
Bahrain’s King Hamad brought in troops from neighbouring Sunni GCC states to restore order and crush dissent in March 2011.
In a separate development on Monday, a court in Manama handed down prison sentences to another two online activists accused of "defaming" the king in comments posted on Twitter.
One defendant was given a four-month sentence while the other was given one month. Their names have not been released.
They were among four people arrested last month on the same charges. Appearing in court on 22 October, they all denied any wrongdoing.
A third activist was imprisoned for six months by the court on Friday, while a verdict in the case of the fourth is expected later this month.
