The reference to Blasphemy has been officially removed from the constitution.
President Michael D Higgins says he has signed the Thirty-seventh Amendment of the Constitution Bill making it law.
Last month's referendum saw the amendment passed by a majority of nearly 65%.
A total of 951,650 (64.85%) people voted for the change, with 515,808 (35.15%) opposing the move.
Nobody has been prosecuted for the offence in Ireland since 1855, in connection with an alleged case of Bible-burning.
It was included in anti-defamation legislation passed by the Government in 2009.
Blasphemy was defined as publishing or uttering something “grossly abusive or insulting in relation to matters sacred by any religion, thereby intentionally causing outrage among a substantial number of adherents of that religion”.
Anybody found guilty could face a €25,000 fine.
