French Lyrics:

Je suis le petit chevalier
avec le ciel dessus mes yeux
je ne peux pas me effrayer

Je suis le petit chevalier
avec la terre dessous mes pieds
j'irai te visiter
j'irai te visiter

English Lyrics:

I am the little knight
with the sky up above my eyes
I cannot be scared

I am the little knight
with the earth down below my feet
I shall visit you
I shall visit you

Thank you to Bjork.com Lyrics 

Bjork sang Le Petit Chevalier live only twice:

For more information, set lists and pictures from these gigs, visit the bjork.com gigography. 

Thank you to Bjorkish.net for these pictures.

The original  Le Petit Chevalier is from Nico's album Desertshore.

It was recorded at Studios Davout, in Paris during 1970. Produced and arranged by John Cale.

The version by Nico was in fact sung by her son. His father is the famous French actor Alain Delon. (thank you chevalierrobin).

Who is Nico? 

Nico was born in 1938 in Germany. She started a modeling career at a young age and moved into films in 1960. When she was 15 she met a photographer who gave her the name, Nico, after his boyfriend. She liked it more than her real name, Christa Päffgen, because it sounded less German. Her fame as a musician began when she met Andy Warhol who put her to work with the Velvet Underground in 1967. Their most influential album, The Banana Album, features her on three songs. Nico left the underground to pursue a solo career and Desertshore was released in 1970. In the 1980's she became addicted to heroine and in 1988 she died in a tragic bike accident. 

sources: 

info and picture: Nico Web Site
info:Swingin Chicks of the 60's