The centre-back struggled for opportunities at the start of the campaign, but he has played in the Hammers' last three fixtures in the Premier League.
Tomkins now admits that the faith shown in him by manager Sam Allardyce has given him a confidence boost.
"It can be frustrating at times when you're sitting on the bench, but I'm growing in confidence with this run of games that I'm getting," he told the club's official website.
"I love playing for West Ham and hopefully I can help us bounce back at Swansea [City]."
West Ham, who are currently in 15th place in the Premier League table, travel to the Liberty Stadium on Sunday.