Williams (2005–2009) 2005 In April 2005, Rosberg was signed by Williams as its second test driver. After race driver
Nick Heidfeld was injured in a bicycle accident in September, Rosberg was shortlisted by Williams as his potential replacement for the final two races, the and the . The team opted for Pizzonia because they did not want to risk delaying Rosberg's career by one to two years if he had a poor performance.
2006–2007 Bernie Ecclestone, Formula One's commercial rights owner, said to Williams team principal and founder
Frank Williams he thought it would be advantageous to sign Rosberg as part of a campaign to bring energetic drivers to the sport. Williams told Rosberg in October 2005 that he was assured of a role on the team as either a racer or test driver for after
British American Racing's
Jenson Button was released from a contract with the team.
Autosport reported Rosberg signed a contract that month to race for Williams in 2006 allowing the team to provide him with as much car acclimatisation as possible. The following month, Rosberg signed a five-year contract with Williams, being selected by Frank Williams for his driving ability, his knowledge of Formula One technology, and for articulately communicating data to engineers. He was told of the news by his father in advance. Rosberg was paid £500,000 by Williams and was the first son of a former world champion in Formula One since
Damon Hill in . To prepare for the season, he achieved the highest score ever in Williams's Engineering Aptitude Test, which tests a new driver's knowledge of car mechanics and engineering aspects of Formula One,
Tony Ross was assigned as his
race engineer. He scored points once more during the season with a seventh at the Rosberg was outpaced by his teammate
Mark Webber, He finished with four points for 17th in the
World Drivers' Championship (WDC). He and his father mutually agreed to stop working with each other, and began working with a sports psychologist. Rosberg's performances improved greatly from 2006 due to Williams restructuring itself and employing more experienced and capable personnel, Rosberg also gained experience in controlling his emotions without losing speed,
2008–2009 The 2008 season was the first in which Rosberg was the more experienced driver on his team, being partnered by Williams test driver
Kazuki Nakajima. He began the season by finishing third at the , the first podium finish of his career. Rosberg was occasionally outperformed by Nakajima, and driver errors lost him chances to score more points; he was able to adapt to a ban on
traction control from Formula One. He improved the best result of his career with a second at the inaugural 14 races later, and finished 13th in the WDC with 17 points. He lost five percent of his body weight to compensate for the introduction of the
kinetic energy recovery systems increasing the car's minimum weight limit to . Rosberg had an improved season: the
Williams FW31 was one of three cars to have an early speed advantage because it featured a
double diffuser system and Rosberg led the first 15 laps of the Malaysian Grand Prix, however, the team could not sustain the car's pace of development. He finished 16 of 17 rounds; the exception was the . Rosberg was consistent in finishing in the points-paying positions, achieving a season-best result of fourth at the and the following . He scored 34.5 points for seventh in the WDC. Rosberg also talked to McLaren and Williams about potential employment; he was skeptical because Williams was mulling over whether
Renault or Cosworth should be the team's engine supplier. On 29 October, he confirmed his departure from Williams at the conclusion of the season and was officially released from his contract with the team on 1 January 2010. One week later Mercedes purchased 75 percent of Brawn GP and entered Formula One under its own name, employing Rosberg to drive for the team. Rosberg was mentored by Mercedes team principal
Ross Brawn and was apprehensive when Schumacher joined the team, given the history of Brawn and Schumacher's relationship at
Ferrari. He was concerned that Schumacher would dominate the team, and in early strategy meetings, found that his own strategy was being discussed with Schumacher more than with him. He felt that Schumacher was constantly acting to cause him minor stress or to assert dominance. Rosberg finished in third place at the , the , and the . Rosberg was seventh in the WDC with 142 points. He finished no higher than fifth in the season's 19 rounds and was seventh in the WDC with 89 points. In November 2011, he signed a contract extension to remain at Mercedes until after . An important factor in Rosberg's decision was the Mercedes team undergoing a technical restructure, which saw the appointments of
Bob Bell as technical director and
Geoff Willis as head of technology in mid-2011. Other reasons included his belief Mercedes would be able to improve their performance and challenge for race victories. Three-time world champion
Niki Lauda began to advise Rosberg. At the , the season's third round, he took the first pole position of his career and his maiden career victory. He then challenged
Red Bull's Mark Webber for the victory at the three races later before he settled for a second-place finish. Rosberg had accumulated more championship points than any other driver in the season's previous four races and emerged as an unlikely contender for the WDC. Notwithstanding this, he achieved one further top-five finish during the season. He was ninth in the WDC with 93 points. He was granted equal status by Mercedes and received no preferential treatment alongside Hamilton. During the pre-season period, Rosberg visited the Mercedes factory in
Brackley, England, displaying a fascination with the
F1 W04's technological development and assisting the team in the car's development. Rosberg challenged his teammate Hamilton during the season qualifying higher eight times and finishing more often. At the , the season's second race, a minor controversy came about when Mercedes invoked
team orders on him to stay behind Hamilton. Unhappy with the decision, He then won the for his third career victory after Red Bull driver
Sebastian Vettel suffered a broken
gearbox. Thereafter, Rosberg earned points in nine of the season's ten final rounds with consecutive podium finishes— second at the and third at the . He finished sixth in the WDC with 171 points and three pole positions. Rosberg's results over the season earned him additional respect within the Formula One community. He was regarded as a favourite for the WDC because of the team's development of the
F1 W05 Hybrid car and adaptation to the technical regulations mandating the use of
turbo-hybrid engines in pre-season testing at the Bahrain International Circuit and the Circuit de Barcelona-Catalunya. Rosberg won the to take the lead of the WDC and finished second in the next four races but Hamilton's four straight victories lost Rosberg the championship lead. Rosberg won the for the second year in succession to regain the points lead after qualifying on pole position in contentious circumstances. Rosberg took four consecutive podium finishes and won the to ensure the championship would be decided at the season-ending . Hamilton was already ahead of Rosberg on track and leading the race when an energy recovery system failure meant Rosberg scored no points for second in the WDC with 317 points. During the off-season he sought to correct a body deficiency, which caused him to hold his breath against
g-forces in high-speed corners, since he did not want to limit the flow of oxygen to his brain and muscles. After four top-three podium finishes in the first four races, which came as his overall performance lowered from focusing more on the race than on qualifying; Vettel threatened Rosberg's hold on second overall. but wins in the final three races in
Mexico,
Brazil and
Abu Dhabi and six consecutive pole positions placed him runner-up overall with 322 points. He altered his racing gloves to improve his starts, removed paint from his helmet to make it lighter that slightly improved his performance, employed a mental trainer to increase his aggression, and spent his spare time go-karting to maintain his ability. Rosberg eschewed
Facebook for five months, studied philosophy, meditated to stay concentrated, and received detailed technical input from Mercedes's mechanics at its headquarters in Brackley, England. He worked with his sports psychologist for up to eight hours per week with two hours of mental discipline every two days. Rosberg carried over his form from end of the 2015 season, winning the first four races to lead Hamilton by 43 championship points although Hamilton suffered reliability issues in two of those first four races. Rosberg and Hamilton made high-speed contact at the after which Hamilton took the championship lead from Rosberg over the next eight races after sub-par results from the former. During the mid-season interval, Mercedes
non-executive chairman Niki Lauda paid a special visit to Rosberg's home in
Ibiza, to help Rosberg regain his confidence and to bounce back. Rosberg changed his diet to remove sugars from his body and abstained from alcohol. he refrained from cycling, losing of muscle in both his legs. He went on to win in
Belgium,
Singapore and
Japan, and achieved three-second-place finishes in a row to enter the season-ending leading Hamilton by 12 points. He won the WDC by five points with a second-place finish after withstanding Hamilton's attempts to back him into the chasing pack and encourage drivers to pass Rosberg to claim the title for himself. Rosberg became the second son of a former world champion to win the title since Damon Hill replicated his father
Graham Hill in . He published a limited-edition book entitled
Finally about the 2016 season on 24 December 2016. Overall, Rosberg competed in 206 races: he won 23, achieved 30 pole positions, gained 57 podium finishes, and scored 1594.5 championship points. ==Retirement from racing and subsequent ventures (2016–present)==