Bontenbal was born in Vreewijk, Rotterdam as the fourth in a family of eight children and grew up in its southern borough of IJsselmonde (initially in the Lombardijen neighborhood).

[9] In 2011 – after four years at DWA – he took a job as a policy officer for the CDA's caucus in the House of Representatives, focusing on sustainability, energy, and the environment.

Bontenbal became an independent consultant specialized in renewable energy generation in 2013 and served at the same time as a junior fellow of the CDA's scientific bureau.

[3][13] Bontenbal has supported an energy transition away from natural gas and has called it necessary to consider biomass and nuclear power for achieving climate goals.

[17] In 2019, when the third Rutte cabinet was struggling with reactive nitrogen emissions, Bontenbal told Trouw that the CDA would not have a future if it would keep advertising itself as a party for the countryside.

[26] That same month, he said that it might be necessary for the government to buy Tata Steel's blast furnace in IJmuiden either partly or in its entirety in order to make it more sustainable.

[27] Together with Silvio Erkens (VVD), Bontenbal pled for two new nuclear reactors – as was agreed upon in the coalition agreement – to be constructed and operated by a new state-owned company that would also seek private investment.

Their recommendations included mandating energy suppliers to offer fixed contracts, forbidding them to give discounts to new customers, and subjecting them to a yearly stress test as well as strengthening consumer protections in case of bankruptcy.

[30] A motion by Bontenbal and Suzanne Kröger (GroenLinks) later passed the House that called on the government to prohibit door-to-door and over-the-phone sales of energy contracts.

[31] Furthermore, following a call by the Consumentenbond, Bontenbal filed a motion to force the government to investigate a potential ban on loot boxes – purchases of randomized prizes in video games – out of a concern for gambling addiction among children.

[36] In his acceptance speech, he said that inequality had risen to high levels and that liberal and progressive parties centered around the individual, while he believed the CDA's campaign should revolve around a sense of community, values and norms, decency, solidarity, and responsibility.

[46] He revised the CDA's stance on consumer fireworks at New Year by supporting a nationwide ban, citing their use in violent acts against first responders.

[47] When the right-wing Schoof cabinet presented its 2025 budget that included €2 billion in education cuts, Bontenbal formed the self-named "unholy alliance" with centrist and conservative opposition parties.

[51] Bishop Johannes Hendriks criticized him in 2024 for receiving Holy Communion when he visited an abbey as part of a television show, as Bontenbal has not been initiated in the Catholic Church.