[4] Lion graduated with a BA in economics and accounting from Bar-Ilan University, and interned in the office of Avigdor Yitzhaki, receiving his CPA in 1990.

[6] In 1996, Lion was appointed managing director of the Prime Minister's Office of Benjamin Netanyahu, also becoming his economic adviser, serving in those roles till 1999.

Lion was chosen to help negotiate the forming of a government coalition following the Israeli elections of 2013, in the aftermath of which the Likud and Yisrael Beitenu parties joined together.

[12] As part of the coalition agreement signed between the two, he began to serve as a member of the city administration, and as the holder of the community management portfolio.

[14] Despite his broad Haredi political support, a coalition of Hasidic and extremist-Haredi Jerusalem Faction leaders declined to endorse Lion, citing his close ties to politician Avigdor Lieberman.

[15][16] In the six-candidate general election held on 30 October 2018, Lion garnered 33% of the vote, while fellow Jerusalem city councilman Ofer Berkovitch finished in second place, with 29%.