The Little Women star arrived on the red carpet wearing a taupe shimmering dress with a thigh-high slit.
Ronan, who is up for an award for best actress in a drama, paired the outfit with strappy nude sandals and sleek hair - a look that has many fans praising the star as the best-dressed of the night.
“Saoirse Ronan wins the Golden Globes,” one person tweeted.
Another said: “Just saw pictures of Saoirse Ronan on the red carpet and I’m too stunned to speak.”
“I don't want to say that Saoirse Ronan is the best dressed tonight but she is,” someone else wrote.
After the Golden Globes nominations were announced, Ronan credited Little Women director Greta Gerwig in her thank you statement to the Hollywood Foreign Press Association.
“Getting to play Jo March, one of the most inspiring characters in literature, still today, has been an honour.
"I am eternally grateful to Greta Gerwig for her guidance and partnership, and for her fierce perseverance that brought this incredible cast together and created an environment for us to become a real family and tell this very special story,” Ronan said in her statement.
“My performance in this film belongs to Greta as much as it does myself and I share this recognition completely with her.”
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