On Tuesday the senate voted in favour of a reform to adoption laws, reported news agency ATS.
Under the proposal, a gay person in a civil partnership could adopt their partner's children from a previous relationship.
The changes would also apply to straight, unmarried people in relationships.
Currently if a person wants to adopt their partner's child they have to be married to them for five years.
Gay marriage is not legal in Switzerland.
Though it must still be approved by parliament and probably a popular referendum, Tuesday's senate vote is a move towards equal rights.
In a 2005 referendum the Swiss people voted to allow registered civil partnerships for same-sex couples, but stipulated that they should not be able to adopt.
“Has the situation in Switzerland changed that fast?” asked Beat Rieder of the centre Christian Democrat Party, reports ATS.
Rieder denounced the move as a ‘salami' tactic which would progress to adoption for single gay people and surrogacy, which is currently illegal in Switzerland.
Those in favour of the changes said it would help protect children should they lose a biological parent, said ATS.
Also under the proposed changes, the minimum age for adoption by a single person will drop to 28, while couples need only be married for three years instead of five.
Switzerland lags behind many other European countries on many aspects of gay rights. Countries including France, Britain, the Netherlands and Ireland all allow gay marriage, and many allow gay adoption.
But Bastian Baumann, of gay rights group Pink Cross, told The Local he was "cautiously optimistic" about the prospects for reform in Switzerland.
"I think our society is way ahead of our politics in some topics like changing marriage rights or adoption rights. The world will not stand still and the politics need to hurry so they don't lose sight."
"At the moment there is a lot going on and adoption rights are a big step in the right direction."
"We need legal marriage for everyone and anti-discrimination laws. But I really can imagine that in ten years all of this has changed."