Vainio began his motorsport career in karting in 1998 and remained active until 2009 in this sport. He won several karting championship: Among other things, 2007, the Finnish Junior ICA Kart Championship, the 2008 CIK -FIA KF3 - European as well as 2009, the CIK - FIA KF1 European Championship. He was also runner-up in the 2009 CIK -FIA Karting World Championship.
2010 Vainio moved into formula racing, and stood in for Tech 1 Racing in the Formula Renault 2.0 Eurocup. A total of seven races he was seen with a podium placement. However, a victory was denied him. At the end of the season, he took a position behind his teammate Arthur Pic fourth place in the drivers' standings. He was also the bestplatzierteste newcomers. In addition, he took up to two races of the British Formula Renault and was 28th in the overall standings. 2011 Vainio went for Tech 1 Racing in the GP3 Series at the start. With a third place as best result he was 15th in the overall standings. In 2012, he moved to Lotus GP and denied his second GP3 season. Vainio won the feature race in Monaco and finished the season in fourth place in the drivers' rating. He defeated team internally Daniel Abt, who finished second overall had become. Following the GP3 season Vainio received the team RFR a cockpit in the 2012 season of Formula Renault 3.5. He played three race weekends and achieved a podium with a third place ranking. In the overall standings he was 18th in 2013 graduated Vainio his third season in the GP3 Series for Koiranen GP that were entered for this season in the series. At the season opener at the Circuit de Catalunya, he won the sprint race at the Hungaroring, the main race. However, he was defeated team internally Kevin Korjus, who had remained winless. Vainio came last weekend no longer used and finished the season in ninth place overall.
Vainio is managed by Nicolas Todt.
- 2011: GP3 Series ( No. 15 )
- 2012: GP3 series ( 4th place)
- 2012: Formula Renault 3.5 ( 18th place)
- 2013: GP3 Series ( course 9 )