Turnout in the poll - which had been planned for October - was low as many people decided to stay away.
Those who came to polling stations had their temperature taken, were told to stand a metre (3ft) apart and wash their hands before and after voting.
Ebola has killed more than 7,373 people in West Africa - with 3,346 deaths in Liberia, the UN says.
Among the 139 candidates vying for 15 seats were former football star George Weah and Robert Sirleaf, the son of Liberia's president.
The election was held just days after neighbouring Sierra Leone clamped down on public gatherings.
It has banned Sunday trading, restricted travel between districts and prohibited public celebrations over Christmas and the New Year.One of Sierra Leone's top doctors, Victor Willoughby, died from Ebola on Thursday, just hours after the arrival of experimental drug ZMab which could have been used to treat him.
Healthcare workers are among those most at risk of catching Ebola which is spread by bodily fluids and requires close contact with victims.
In November, Liberia's election commission chairman, Jerome Korkoya, urged candidates and supporters to follow public health regulations in the run-up to the senate elections.
"For instance, the transportation of large groups of electorates by candidates clustered in vehicles and the congregation of huge number of people will be regulated," he said in a statement.
UN Secretary-General Ban Ki-moon was in Liberia on Friday at the start of a two-day visit to countries affected by Ebola in West Africa. He continued on to Guinea on Saturday.After stepping off the plane, he washed his hands and had his temperature taken - two important practices to help stop the spread of the disease.
Mr Ban urged people to follow strict health regulations until the epidemic was over.
Liberian President Ellen Johnson Sirleaf lifted a state of emergency last month that was imposed in August to control the outbreak.
