During his first term in the Knesset, Erdan was one of the most outspoken opponents of the unilateral Disengagement Plan from the Gaza Strip led by Prime Minister Ariel Sharon from the Likud.

[8][9] As Minister of Environmental Protection, Erdan introduced the most comprehensive River Restoration program to date,[10] legislated and enforced the protection of beaches and the coastline,[11] increased recycling through a bottling and packaging law,[12] and created the Beer Sheva River Park – an ecological park built on a former garbage dump – where thousands of people enjoy bike paths, walking trails, a lake, sports area, and a botanical garden.

[15] In May 2009, Erdan was declared "man of the decade" by Or Yarok, a prominent road safety NGO in Israel, for his lasting efforts to reduce traffic accidents and fatalities.

Erdan's appointment came eleven days after he initially refused to join Netanyahu's cabinet, claiming he wasn't offered enough tools to make a real change as a Minister.

Upon entering his role, the state of Israel started facing a new wave of Palestinian terror attacks, carried out mainly by incited individuals,[19] and commonly referred to as the "Knife Intifada".

In addition, Erdan initiated the construction and opening of new police stations in East Jerusalem, signaling to the residents of its neighborhoods that the state of Israel will not give up its sovereignty in these areas.

[21] In his attempts to deal with online incitement against Israelis and Jews by Palestinians, which often could lead to terror attacks, Erdan and his colleague, Minister of Justice Ayelet Shaked, proposed the so-called Facebook bill that will enable Israeli courts to issue decrees against social media companies like Facebook, Google or Twitter to remove public content deemed to be a threat to national security, public security, or a violation of the law, in case the social media company failed to detect and remove the content on its own.

[22][23] However, following the submission of the bill, a senior delegation from Facebook arrived in Israel to meet with Erdan, agreeing to work together in order to improve the detection and removal of inciting material online.

The reform, which was recommended by a professional committee appointed by Erdan, was called "Responsible Decriminalization", since it didn't go all the way to legalize Cannabis, but instead made private recreational use punishable by fines.

[25] The rationale for this move, explained Erdan, was to prevent unnecessary arrests and criminal records on one hand, while retaining deterrence from usage of Cannabis in the public sphere.

[33] On 31 October 2023, Erdan, as well as other Israeli delegates, began wearing yellow star badges with the words "Never Again" written on them, in response to international criticism of Israel's conduct during the Israel–Hamas war.

[34] This action was immediately condemned by Yad Vashem chairman Dani Dayan, who called it a "[disgrace to] the victims of the Holocaust as well as the state of Israel," while adding "The slaughter of Jews by Hamas on October 7th was genocidal in its intents and immeasurably brutal in its form.

"[35][36] According to Ynet, unnamed officials from Israel's Ministry of Foreign Affairs were also highly critical of the decision, with one calling it a "cheap gimmick that doesn't serve our goal", and others describing it as an attempt to appeal to Likud party members.

[37] On 8 December 2023, Erdan thanked the United States for vetoing a UN Security Council resolution calling for an immediate humanitarian ceasefire in the Gaza Strip.

Before the vote he illustrated this by running a copy of the UN charter through a paper shredder while giving a speech for the UN General Assembly, referring to the Holocaust, World War II, and Hitler.