Nikolaisen was educated at the Royal Art Academy in 1916 where he was a pupil of Rostrup Boyesen. After his studies he travelled to Paris where he was greatly inspired by the great French impressionists. Nicolajsen was also inspired by the Danish artists L.A Ring and Hammershöj. Nicolajsen is known for his colourful landscapes and detailed portraits. During the summer months Nicolaisen travelled in Denmark where he did a long series of sunlit landscapes from the villages Lejre and Odsherred. During the winter months Nikolajsen preferred staying in Copenhagen where he did cityscapes and portraits.
Charlottenborg: 1938, 1940 and 1957.
The National Museum of Art: 1941
Danish art exhibition in Oslo, Norway: 1948
Danish art exhibition in Göteborg, Sweden: 1955