[1] Seelig was born to Karl Wilhelm, a proprietor of a silk dye works and a mountaineer, and Julie Alwine née Kuhn.
Seeling then began publishing independent literature as a theatre and film reviewer, editor, and author.
[3] Seelig's recorded correspondents were, among others, Max Brod, Hans Henny Jahnn, Alfred Polgar and Joseph Roth.
He also maintained close contacts with Swiss authors, most notably Robert Walser, whom he accompanied on his walks, giving rise to the biographical work, Wanderungen mit Robert Walser, The Swiss Literary Archives store, as a long-term loan, approximately 6,000 manuscript pieces by Seelig.
As a testament to his dedication, he played a pivotal role in establishing the Carl Seelig Foundation in 1966.