Labour's Tristram Hunt is to stand down as MP for Stoke-on-Trent Central to become the director of the V&A museum in London.
The former shadow education secretary said he had "no desire to rock the boat" and insisted anyone who interpreted his decision to quit that way is "just plain wrong".
But Mr Hunt said he had become frustrated over how Labour should respond to the shockwaves to have hit mainstream politics.
In a letter to local party members, he wrote: "As I enter a new role as a public servant, I will be leaving partisan politics behind me and will work impartially as a museum director.
"I am sorry to put you, the party and the people of Stoke-on-Trent through a by-election.
"I have no desire to rock the boat now and anyone who interprets my decision to leave in that way is just plain wrong."
Mr Hunt said serving in Parliament had been "both deeply rewarding and intensely frustrating" and told of the "harrowing effects of poverty and inequality" he had seen during his work as an MP.
He added: "The frustration, of course, came with the inability to address those factors and implement our policy programme following our defeat in 2015 - and, more broadly, about how the Labour Party should respond to the social, cultural and economic forces which have rocked mainstream social democratic and socialist parties from India to Greece to America.
"There were very few jobs that would have convinced me to stand down as MP for Stoke-on-Trent Central, but the post of director of the V&A - the world's greatest museum of art, design and performance - is just that."
A spokesman for Labour leader Jeremy Corbyn said: "Jeremy would like to thank Tristram Hunt for his service to the people of Stoke-on-Trent Central and to the Labour Party. Jeremy wishes him well in his future pursuits at the V&A."