The 32-year-old made 112 appearances for Boro, who he joined from West Ham in the summer of 2017 for a reported £5million fee (BBC Sport).
Randolph thoroughly impressed for the Teesside club and won Player of the Year last season, was named in the Championship Team of the Year, and also made the club's Team of the Decade.
However, injuries have restricted Randolph's appearances this season for Boro as academy graduate Aynsley Pears stepped up into the goalkeeping role and has been doing well.
West Ham, meanwhile, were in the market for a new keeper this month, with Lukasz Fabianski recently returning to the side after injury and question marks over the performances of deputies Roberto and David Martin.
On Wednesday, both clubs confirmed that Randolph had rejoined the London Stadium side on a three-and-a-half-year contract, for a reported fee of around £4million (BBC Sport).
Here is what some Boro fans have been saying on social media:
I am not crying you are— Leo (@Leo_Broadley104) January 15, 2020
Here’s to you Darren Randolph, Boro loves you more than you will know— ryanwalker04 (@ryanwalker04) January 15, 2020
Unfortunate. But hopefully will help us in the long run and get the finances back on track!— Alex Burnip (@alexburnip) January 15, 2020
Enjoy the bench, good luck.— Lee (@Boston1960Lee) January 15, 2020
I’m not crying u are— Joe (@Joe__MFC) January 15, 2020
Best keeper we’ve had in a long time. Good luck randz you were unreal . Time for aynsley to smash it— Charlie (@CharlieMFC__) January 15, 2020
:(— Jack (Mr Mab Stan) (@LewisWing) January 15, 2020
Im not surprised in the slightest. We knew this was coming.— JosephCoombs (@Coombs2Joseph) January 15, 2020
On the plus Pears has shown he's capable of holding the mantle
@RandzOfficial Good luck Darren, all the best back at West Ham we will miss you! ⚪️— Jason Lincoln (@JasonLincoln) January 15, 2020
I'm not to concerned about him going. Good keeper but wants to be away and we should recoup what we paid for him. Frees up some money on the wage bill to hopefully be used to strengthen the squad.— Paul Stephens (@PaulStephens_) January 15, 2020
Good luck thanks for your quite brilliant displays for us— Craggsy (@Craggsy) January 15, 2020
Good luck @RandzOfficial one of the best keepers I’ve seen pull on the shirt. Great servant, good luck!!— Shaun Langshaw (@shaunl83) January 15, 2020
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