Gustaf Lagerbjelke was born 6 October 1817 on Skeppsholmen, Stockholm, to colonel Axel Lagerbjelke, 2nd Count Lagerbjelke and baroness Carolina Antoinetta Cederström.[2] After his father's death in 1832, he became 3rd Count Lagerbjelke.[2] Lagerbjelke studied at Uppsala University, where he became Juris utriusque kandidat in December 1838.[2] Between 1844 and 1866, he served in the Riksdag of the Estates for the Lagerbjelke family.[2]
Along with Henning Hamilton, Gillis Bildt and Eric Josias Sparre [sv], Lagerbjelke became one of the leaders of the Junker Party, and was the party's authority on constitutional and formal issues. In connection with the representation reform as the country moved to a parliamentary system, he submitted his own proposal, but it was not adopted.[3]
Lagerbjelke married countess Sofia Albertina Snoilsky, daughter of commander count Gustaf Snoilsky and Ulrika Juliana Lode, in Stockholm on 5 December 1843.[2] After her death in 1847, he married Ebba Augusta Henriette Ribbing, daughter of rittmeister Bengt Ribbing and Augusta Christina Schmiterlöw, on 19 July 1859 on Liljeholmen in Jönköping.[2]
