Goldblum was the spokesperson of Peace Now from 1980 to 2000. He was in the front line of the demonstration when Peace Now protester Emil Grunzweig was murdered. He later identified the incident as a "catalyst" for greater political activism. Goldblum initiated the Settlements Watch activities of Peace Now in 1990. In 1995, Goldblum, referring to the Israeli cabinet decision to expand the settlements, said, "We believe that this decision is going to bring a tremendous clash with the Palestinians." In a 2001 interview after the beginning of the Second Intifada, Goldblum discussed the name of the organization Peace Now, saying "The name is very problematic. Today I would not choose the same name for the movement, but we cant change it now. I find this name extremely difficult and it is even a source of embarrassment for me. I cant even put the movement's sticker on my car."
In October 2012, Goldblum and his family foundation, the Yisraela Fund paid for and were involved (along with other Israeli academics) in commissioning a controversial poll regarding Israeli attitudes towards prejudice, along with Mordechai Bar-On, Ilan Baruch, Alon Liel, and  Michael Sfard. In a press release of the commissioning group, sent by Goldblum, it was stated, "a large part of the Jewish population (58%) accepts the application of the term apartheid to the current state of affairs in Israel. It is, however, not clear what these respondents understand by the term as this question did not require clarification." Goldblum also acknowledged there were problems with a question used on the poll. Israeli statistician Camil Fuchs, who supervised the company that conducted the poll, told The Times of Israel that the questions in the poll were fine and did not need changing by the Dialog team.
In January 2013 Goldblum was #87 on the candidates list of Meretz, for the Knesset elections.
In February 2013, Goldblum was one of the organizers of a gathering  at the Van Leer Institute in Jerusalem which discussed apartheid in the Israeli context. A new NGO,  The Organization for the Prevention of Apartheid in Israel, was established to expose and fight against trends of racism and apartheid in Israel.
Due to his political views, Goldblum decided in April 2020 to leave the International Council of the New Israel Fund saying that he "left in order to be free and independent, in order not to attribute to NIF anything that I say which is different than what NIF says". New Israel Fund denied a report on Makor Rishon claiming that "NIF dissociated itself from Goldblum in the wake of his derogatory remarks about Israeli settlers and right wing figures". NIF reacted by declaring that "Contrary to what is said in this report, NIF did not take any steps against Prof. Goldblum, Goldblum was not rejected from the International Council, NIF did not dissociate itself from him and did not request to do so. As Goldblum said, he requested to leave on his own will. Prof. Goldblum is a person of countless virtues who devoted all his life to voluntary activism for the sake of Peace and Equality, for the sake of the State of Israel, The Israeli Society and for the New Israel Fund and we thank him for that".