The cases provide a further test for the European court, which has in the past allowed member states considerable leeway concerning workplace tolerance of religious beliefs and symbols.
The plaintiffs, aged 51 to 61, told the European Court of Human Rights, based in the eastern French city of Strasbourg, that British law discriminated against them and failed to protect their religious freedom at the workplace.
A decision from the court, a body under the aegis of the Council of Europe, could take several months.
One plaintiff, Nadia Eweida, was sent home without pay from British Airways in 2006 for wearing a small silver cross around her neck that violated the company's dress code.
"Considering that we spend 80% of our time at work, what would be the value of a right that stops the minute one enters the workplace?" Eweida's lawyer, James Dingemans, argued.
Dingemans told the rights court his client worked alongside colleagues who were allowed to wear religious symbols such as the Sikh turban, the Muslim headscarf or the Jewish skullcap.
In a similar incident, nurse Shirley Chaplin was told by her employers to remove a crucifix around her neck as it could cause injury if a patient pulled at it.
Both of their cases were dismissed by British labour courts.
The European court was also asked to rule on two other cases focusing on the tasks employees were asked to carry out at work. Those claims had also been rejected by Britain's labour courts.
One plaintiff, Gary McFarlane, was dismissed from a national counselling service when his employers judged him unwilling to offer sex advice to homosexual couples. Another, Lilian Ladele, refused to officiate at civil partnership ceremonies for gay couples as part of her duties as a registrar.
A lawyer for the British government made a distinction between religious practices protected by the state and the display of personal convictions that can be regulated.
"The petitioners had the possibility of expressing their religious convictions outside of the professional sphere," lawyer James Eadie told the court.
The human rights court has in the past given considerable leeway to member states to regulate the wearing of religious dress and display religious symbols in public, especially in cases involving Islamic dress.
In one previous case, the court ruled that a French school could make its Muslim students remove their headscarves during sports classes for safety reasons. In another, it found that an Italian state school did not violate the rights to religious freedom or education by displaying crucifixes in classrooms.
Rulings by the human rights court cannot be appealed and signatories must comply or risk exclusion from the Council of Europe.