Major League Baseball will boost US telecast revenue by more than double under new eight-year agreements announced on Tuesday that begin in 2014 and with an earlier deal produce a combined $US12.4 billion ($A12 billion).

The total income amount, reported on Major League Baseball's website, includes an ESPN cable television deal announced in August as well as the contract renewals with Fox and TBS that include digital streaming rights.

That means the new deals through 2021 bring better than a 100 per cent boost over the current deals that expire next year.

"To see the unprecedented and historic commitment these networks have made to televising Major League Baseball for years to come is truly amazing," said Major League Baseball commissioner Bud Selig.

Fox retains World Series and All-Star Game telecast rights plus those in a league championship series and two of the four quarter-final series.

Fox will boost Saturday season telecasts from 26 to 52 games.

TBS keeps one league championship series, two quarter-final series and will have new rights for games on the final 13 Sundays of the season.

The announcement came on the penultimate day of this year's six-month regular season.