The Liver Buildings, painted in 1959, has been in private possession for nearly 30 years and has never appeared in a major public exhibition.
Its owner has agreed to lend it to The Lowry gallery in Salford for three years.
Curator Claire Stewart said it was "a beautiful example" of Lowry's work.
It forms part of a new exhibition showcasing more than 100 paintings and drawings by the artist, who was born in Stretford in 1887. Much of his work depicted 20th Century life and scenes in northern England.
His 1960 painting, known as Station Approach, Manchester, was sold last year for Â£2.3m.
Lowry's work was also shown solo abroad for the first time when they were exhibited recently in China.
A rarely seen painting of Liverpool's waterfront by the artist LS Lowry has gone on display for the first time in more than 40 years.