Krohn was born in Nurmijärvi, in the southern Uusimaa region of Finland. Motorsport runs deep in his family: his father Pertti Kurki-Suonio competed in the 1987 Finnish Formula Ford championship alongside future Formula One world champion Mika Häkkinen and Mika Salo, though Pertti's own career never extended beyond Scandinavia beyond a single appearance at the Brands Hatch Formula Ford Festival. Krohn's elder sister Jenni and younger brother Oskari are also professional racing drivers competing in Finland.
Krohn began karting at age six and spent nine years in karts before stepping into car racing in 2005. He made his single-seater debut in Finnish Formula Ford events in 2006, also contesting the Formula Ford Festival at Brands Hatch and finishing as runner-up in the British Formula Ford Winter Series behind David Mayes.
In 2007 Krohn entered the full UK Formula Ford championship, finishing 17th, while also competing in Finnish Formula Three, taking six wins to finish second overall in the championship. His breakthrough came in 2008, when he won three championships simultaneously: the Finnish, Northern European Zone (NEZ), and Estonian Formula Renault titles, recording ten wins in total across those campaigns. A drive in the UK Formula Renault championship followed, where he recorded a win at Thruxton.
A notable moment from his 2009 UK Formula Renault season came at Donington Park, where Krohn climbed from 25th to 7th in wet conditions before a suspension failure forced him to complete the final three laps on three wheels.
In 2014, Krohn was admitted to the BMW Motorsport Junior Programme, spending three years training alongside established works drivers including Dirk Adorf and Jörg Müller. His development within the programme culminated in a significant result in endurance racing: partnering Jun San Chen in the FIST-Team AAI BMW M6 GT3, Krohn won the 2017–18 Asian Le Mans Series GT Drivers title. That championship victory earned him promotion to full BMW works driver status in 2018.
Following his elevation to works driver, Krohn became a regular in the IMSA SportsCar Championship with BMW, competing in the GTLM class. He was consistently paired with American driver John Edwards as his primary co-driver, with Augusto Farfus and Nicky Catsburg joining for endurance events. The pairing campaigned the BMW M8 GTE through the IMSA seasons. Krohn also maintained a busy schedule in European GT competition, including the GT World Challenge Europe and the 24 Hours of Nürburgring.
Krohn represents a generation of Scandinavian GT specialists who transitioned from open-wheel junior formulae into the BMW works programme. His father's connection to the same Finnish Formula Ford fields as Mika Häkkinen gives the family a distinctive place in the history of Finnish motorsport. As a BMW works driver competing across IMSA, WEC, and European GT platforms, Krohn has brought consistent professionalism to long-distance GT racing while serving as one of the manufacturer's trusted endurance specialists.