She was the first child and eldest daughter of Louis Rudolph, Duke of Brunswick-Wolfenbüttel, and his wife, Princess Christine Louise of Oettingen-Oettingen.

At age 13 Elisabeth Christine became engaged to the future Charles VI, Holy Roman Emperor, through negotiations between her ambitious grandfather, Anthony Ulrich, Duke of Brunswick-Wolfenbüttel and Charles' sister-in-law, Empress Wilhelmine Amalia, whose father was John Frederick, Duke of Brunswick-Calenberg and thus belonged to another branch of the House of Welf.

[5] At the time of the wedding, Charles was fighting for his claim to the Spanish throne against the French candidate Philip, so he was living in Barcelona.

Elisabeth Christine arrived in Spain in July 1708 and married Charles on 1 August 1708 in the church of Santa María del Mar, Barcelona.

[7] She was an excellent shot and attended shooting matches, participated in hunting while she and her ladies-in-waiting dressed in amazon attire and also played billiards.

In the 1720s, she appeared to have had some influence in the treaty with the Russian tsar through her family connections in Northern Germany, and she allied herself with the court faction which opposed the plans to marry her daughters to members of the Spanish royal house.

[5] Three years after her marriage, court doctors prescribed large doses of liquor to make her more fertile, which gave her face a permanent blush.

[5] After this, the court doctors prescribed a rich diet to increase her fertility, which made her so fat that she became unable to walk, experienced breathing problems, insomnia and dropsy and had to be lowered into her chairs by a specially constructed machine.

As a widow, she never received the large income left to her in the will of Charles because of the crisis of the state, but her daughter Maria Theresa provided a comfortable existence for her court.