Wiechel was elected chairman of the Sweden Democrats in the city of Norrköping as well as the regional board in Östergötland in 2009.

Wiechel returned to local politics in 2023 when he entered as a deputy member of Nacka Municipal Assembly.

Following the resignation of Lars Isovaara on 29 November 2012, Wiechel assumed office as a regular member of parliament.

On 17 July 2021 Wiechel was awarded the Medal of Honour of the National Assembly of Armenia presented by the Armenian ambassador to Sweden Alexander Arzoumanian.

Since 2022, he is the chairman of the Swedish PACE-delegation, first ever as a politician of the Sweden Democrats and in January 2023 he was elected vice president of the whole Assembly.