Merriman is the son of Ted Merriman, who was himself a Saskatchewan Party MLA from 2003 to 2007.^[1] Merriman was born and raised in Toronto. The Merriman family moved to Saskatchewan in 1988, and Paul Merriman has worked in Saskatoon since 1994. He worked for SaskEnergy for nearly a decade, and before entering politics was the executive director of the Saskatoon Food Bank & Learning Centre, where he prioritized cutting costs.^[2] He has also been a small business owner.

Merriman was acclaimed as the Saskatchewan Party candidate for Saskatoon Sutherland ahead of the 2011 election after incumbent Joceline Schriemer announced that she would not be running again.^[1] He was elected in the November general election.^[2] Merriman was re-elected in the 2016 election in the newly established riding of Saskatoon Silverspring-Sutherland, and re-elected in 2020.^[3]

Merriman was named Minister of Social Services in Brad Wall's government in 2017, a role he carried over to Scott Moe's government when Moe succeeded Wall as Premier in 2018. During the federal government's efforts to work with provinces to roll out national childcare in 2019, Merriman was criticized for comments he made stating that provincial ministers should have been able to have meetings with the federal government without Indigenous representatives present, whom Merriman characterized as "lobbyists".^[4] In response, Assembly of First Nations Chief Perry Bellegarde wrote Merriman a letter, explaining that he was also an elected representative. Merriman later said he regretted the use of the term lobbyist.^[5] That same year, Merriman introduced reforms to Saskatchewan's welfare programs. The reform replaced existing programs with a new program called Saskatchewan Income Support (SIS).^[6] Merriman stated that the reform was meant to reduce bureaucracy, increase independence, and prioritize "motivational interviewing" on the part of social workers.^[7] The government also stopped direct rent payments on behalf of program recipients. The reforms were criticized by anti-poverty advocates for actually increasing bureaucracy and offering inadequate support to recipients.^[7][8]

In November 2020, Merriman was named Minister of Health during the province's second wave of the COVID-19 pandemic. Although the province's case numbers were rising, Merriman called them "manageable" and downplayed the need for further public health measures, signalling a prioritization of access to vaccines.^[9] Beginning in late 2020, the province's health care system became severely strained by COVID, ultimately resulting in the province signing agreements to transfer intensive care unit (ICU) patients out-of-province in late 2021.^[10] Merriman was criticized for a lack of availability. In April 2021, Merriman and Moe declined an invitation to tour a Regina ICU; hospital staff had issued the invitation, stating that "If only the leadership would come and see what's really going on here, they would understand what we're dealing with." In response, Merriman stated that he did not think it would be "appropriate" to accept the invitation.^[11] In the summer and fall of 2021, Merriman stopped attending press conferences for more than a month, leading to calls for his resignation, although he claimed to have been working with his staff during this absence.^[12][13] After a 2023 Global News investigation showed that the province's chief medical health officer, Saqib Shahab, had urged the government to implement further public health measures in the fall of 2021 to ease the strain on the health care system—something Shahab had publicly hinted himself at the time^[14]—Merriman declined an interview but stated in question period only that the province had acted on Shahab's advice.^[15][16]

In August 2023, Moe shuffled his cabinet and named Merriman the new Minister of Corrections, Policing and Public Safety.^[17]

Merriman is married to Leanne Durand, and the couple have four children.^[18]

• Profile at the Legislative Assembly of Saskatchewan