After a successful career in karting, Kevin, son of 1994 British F3 Champion and Stewart F1 driver Jan Magnussen, made the switch to single-seaters in 2008, winning the Danish Formula Ford championship with an impressive record of 11 wins, 12 podiums, 6 pole positions and 10 fastest laps.
The following year, he graduated to Formula Renault 2.0, finishing runner-up in the Northern European Cup and seventh in the Eurocup. In the NEC, he scored one win, 12 podiums and two pole positions - achievements that earned him the 'Rookie of the Year' accolade.
In 2010, he moved into German F3, impressing immediately by taking victory in the opening round of the season. It was the first of three victories on his way to securing third in the championship and once again being named 'Rookie of the Year'.
Kevin also joined the McLaren Young Driver programme in 2010, dovetailing his racing activities with training and development work with the legendary F1 team with which his father made his F1 debut - a one-off outing with the Woking team in the 1995 Pacific GP at the Aida Circuit where he replaced Mika Hakkinen who was recovering from appendicitis.
In 2011, he moved into British F3, building upon the successes of the previous season. He finished second in the championship after securing seven race wins, six pole positions and eight fastest laps.
As a result, his F3 team, Carlin Motorsport, signed him up for 2012's World Series by Renault 3.5 series. As a rookie, he won once and took three further podium spots, but the year helped him sharpen his teeth before a full assault on the WSR title in 2013.
With a year's experience under his belt, Kevin underlined both his speed and maturity, slowly tightening his grip on the title, before underlining his supremacy by dominating the series' final two rounds.
It was this blend of assurance, maturity and potential, as well as a pair of stunningly impressive testing outings at Abu Dhabi and Silverstone, that helped him land the drive with McLaren for 2014.
As the first Dane to start an F1 race for a decade - Nicolas Kiesa raced for Minardi at the tail-end of 2003 - a nation's gaze was directed towards him when he lined up on the grid for the season opener.
In pre-season testing the MP4-29 was strong, not least due to the fact that Mercedes had clearly mastered the new formula. Kevin topped the overall times at Jerez and was third overall in the opening test in Bahrain. By the end of the final test he had slipped to sixth, but no cause for alarm.
The season got off to the worst possible start when Kevin and Button finished second and third in Melbourne, courtesy of Ricciardo being disqualified for fuel irregularities.
We say 'worst possible start' because basically this is as good as it got. Though there were some good performances, they were few and far between and never totally convincing. Furthermore, whilst clearly running the best power unit on the grid the spectre of Honda and the 'ghost of season to come', continually hovered over the Woking outfit.
In total the Dane score points in twelve of the season's nineteen rounds, but by the end of the year had totalled around a third of the point scored by his iteammate. Worse, though considered "lightning quick" Kevin was trounced 10-9 in qualifying.
For the most part, Button had the measure of Kevin, the Briton's consistency and experience winning out, particularly in the second half of the season, whilst, other than Russia, the Dane's challenge all but fizzled out.
On December 11, following weeks of speculation, it was confirmed that Fernando Alonso was returning to Woking, the team finally also putting Button (and his fans) out of their misery by confirming the Briton for a sixth season.
Kevin was retained as test and reserve driver, whilst Stoffel Vandoorne was also kept on the books, a fact that would not be lost on the Dane.
Whilst nobody really expected the latest incarnation of the legend that was McLaren-Honda to sweep all before it, rekindling those glory days of the 80s and 90s, surely nobody expected it to be the unmitigated disaster that it was.
The MP4-30 managed just 12 laps over the first two days of pre-season testing at Jerez, and when Alonso completed 32 laps on the third day there was a collective sigh of relief in the McLaren camp, but then came Barcelona.
On the final day of the first Barcelona test, the Spaniard crashed heavily at T3 in circumstances that have never been explained. Indeed, it was the statements then denials that first got people wondering what on earth was going on, a question that was oft repeated over the course of the year.
Ruled out of the opening race of the year, Alonso was replaced by Kevin, who - like his teammates - had had little significant time in the car. Starting from last, the fact the Dane's car broke down on its way to the grid tells you all you need to know.
With Alonso back in the car for the remainder of the season - even though he might well have wished he hadn't been - Kevin focussed on his duties a reserve which mostly meant the simulator.
As the year progressed and Vandoorne looked set to secure the GP2 title, Kevin was the centre of much speculation, and whilst he was said to be under consideration for a 2016 drive the team ultimately decided to retain its 2015 line-up.
Despite being likened to Ayton Senna by Trevor Carlin, Kevin was informed his services would not be needed by McLaren, the Dane given the news on his birthday... by email.
In mid-January, amidst talk that Kevin was said to be considering a number of options including WEC, rumours linking him with the 'new' Renault team began to emerge and it was revealed that the money from PDVSA was overdue, thereby putting Pastor Maldonado's seat in jeopardy.
Venezuela, already in the midst of its worst recession in living memory, the global oil glut, and the resultant effect on prices, inflicted further pain. On February 1, Maldonado took to Twitter to announce that he would not be on the grid in 2016 and with just 48 hours before Renault revealed its new livery and driver line-up, it looked as though Kevin was heading back to the grid.
It's ironic that Kevin was leaving McLaren for Renault, for both teams found themselves with mountains to climb.
The late purchase of Lotus by Renault not only had an impact on the car - the French team forced to use a 2016 Lotus built for a Mercedes engine and using 2015 components - it meant that the manufacturer headed into its 'debut' season almost totally unprepared.
In the final years of Lotus the facility at Enstone had been allowed to fall into disrepair, the workforce seriously depleted, machinery and licenses out of date and all manner of other problems greeted the new owner... and its drivers.
In all fairness, Kevin did the best with the equipment he had at his disposal, which wasn't much. If proof were needed of how bad things were for the Enstone outfit, think about the fact that despite using the same engine as Red Bull, the Austrian team scored two wins and amassed 468 points while the French outfit struggled to score 8.
The Dane did his best, though this often meant overdriving the car. Indeed, for much of the season he appeared to be trying too hard, and consequently paid the price.
In Bahrain, having been forced to start in the pits, he drove a determined race and was unlucky not to make it into the points, the Dane finishing eleventh.
Avoiding the first lap madness in Russia, canny strategy saw the youngster undercut (future teammate) Romain Grosjean to take seventh, giving the team its best result of the year.
Having out-paced his teammate for the first half of the season as Palmer gradually began to find his feet so Magnussen pushed ever harder. Sadly, more often than not this led to mistakes.
While he was the innocent victim of Daniil Kvyat in Monaco - who wasn't at some time or another - his overdriving proved costly in Canada, Italy and Belgium where he crashed heavily whilst battling his teammate.
At times his driving bordered on desperation, surely it was no coincidence that in the wet he was regularly among the first to make the switch to slicks, a risky move at the best of times but even more so when at the wheel of a car with the downforce issues of the Renault. Indeed, in Britain and Brazil the early switch to slicks proved costly.
For 2017 Kevin heads to Haas to join Romain Grosjean, a team that like Renault is having to find its feet.
With Esteban Gutierrez proving a major disappointment in 2016, the American team will be looking to Kevin to contribute as the team moves forward.
Haas has demonstrated not only that it means business but that it is serious about making progress, therefore 2017 is Kevin's chance to shine.